Release 3.0 Date April 18, 2012 This tutorial gives an introduction to writing GTK+ 3 applications in Python. Prior to working through this tutorial, it is recommended that you have a reasonable grasp of the Python programming language. GUI programming introduces new problems compared to interacting with the standard output (console / terminal). It is necessary for you to know how to create and run Python ﬁles, understand basic interpreter errors, and work with strings, integers, ﬂoats and Boolean values. For the more advanced widgets in this tutorial, good knowledge of lists and tuples will be needed. Although this tutorial describes the most important classes and methods within GTK+ 3, it is not supposed to serve as an API reference. Please refer to the GTK+ 3 Reference Manual for a detailed description of the API. Contents:

CONTENTS

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CONTENTS

CHAPTER

ONE

INSTALLATION
The ﬁst step before we start with actual coding consists of setting up PyGObject and its dependencies. PyGObject is a Python module that enables developers to access GObject-based libraries such as GTK+ within Python. It exclusively supports GTK+ version 3 or later. If you want to use GTK+ 2 in your application, use PyGTK, instead.

1.2 Prebuilt Packages
Recent versions of PyGObject and its dependencies are packaged by nearly all major Linux distributions. So, if you use Linux, you can probably get started by installing the package from the ofﬁcial repository for your distribution.

1.3 Installing From Source
The easiest way to install PyGObject from source is using JHBuild. It is designed to easily build source packages and discover what dependencies need to be build and in what order. To setup JHBuild, please follow the JHBuild manual. Once you have installed JHBuild successfully, download the latest conﬁguration from 1 . Copy ﬁles with the sufﬁx .modules to JHBuild’s module directory and the ﬁle sample-tarball.jhbuildrc to ~/.jhbuildrc. If you have not done it before, verify that your build environment is setup correctly by running:
$ jhbuild sanitycheck

It will print any applications and libraries that are currently missing on your system but required for building. You should install those using your distribution’s package repository. A list of package names for different distributions is maintained on the GNOME wiki. Run the command above again to ensure the required tools are present. Executing the following command will build PyGObject and all its dependencies:
$ jhbuild build pygobject
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This example differs from the simple example as we sub-class Gtk.Window to deﬁne our own MyWindow class.

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class MyWindow(Gtk.Window):

In the class’s constructor we have to call the constructor of the super class. In addition, we tell it to set the value of the property title to Hello World.
Gtk.Window.__init__(self, title="Hello World")

The next three lines are used to create a button widget, connect to its clicked signal and add it as child to the top-level window.
self.button = Gtk.Button(label="Click Here") self.button.connect("clicked", self.on_button_clicked) self.add(self.button)

Accordingly, the method on_button_clicked() will be called if you click on the button.
def on_button_clicked(self, widget): print "Hello World"

The last block, outside of the class, is very similar to the simple example above, but instead of creating an instance of the generic Gtk.Window class, we create an instance of MyWindow.

2.2. Extended Example

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CHAPTER

THREE

BASICS
This section will introduce some of the most important aspects of GTK+.

3.1 Main loop and Signals
Like most GUI toolkits, GTK+ uses an event-driven programming model. When the user is doing nothing, GTK+ sits in the main loop and waits for input. If the user performs some action - say, a mouse click - then the main loop “wakes up” and delivers an event to GTK+. When widgets receive an event, they frequently emit one or more signals. Signals notify your program that “something interesting happened” by invoking functions you’ve connected to the signal. Such functions are commonly known as callbacks. When your callbacks are invoked, you would typically take some action - for example, when an Open button is clicked you might display a ﬁle chooser dialog. After a callback ﬁnishes, GTK+ will return to the main loop and await more user input. A generic example is:
handler_id = widget.connect("event", callback, data)

Firstly, widget is an instance of a widget we created earlier. Next, the event we are interested in. Each widget has its own particular events which can occur. For instance, if you have a button you usually want to connect to the “clicked” event. This means that when the button is clicked, the signal is issued. Thirdly, the callback argument is the name of the callback function. It contains the code which runs when signals of the speciﬁed type are issued. Finally, the data argument includes any data which should be passed when the signal is issued. However, this argument is completely optional and can be left out if not required. The function returns a number that identiﬁes this particular signal-callback pair. It is required to disconnect from a signal such that the callback function will not be called during any future or currently ongoing emissions of the signal it has been connected to.
widget.disconnect(handler_id)

Almost all applications will connect to the “delete-event” signal of the top-level window. It is emitted if a user requests that a toplevel window is closed. The default handler for this signal destroys the window, but does not terminate the application. Connecting the “delete-event” signal to the function Gtk.main_quit() will result in the desired behaviour.
window.connect("delete-event", Gtk.main_quit)

Calling Gtk.main_quit() makes the main loop inside of Gtk.main() return.

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3.2 Properties
Properties describe the conﬁguration and state of widgets. As for signals, each widget has its own particular set of properties. For example, a button has the property “label” which contains the text of the label widget inside the button. You can specify the name and value of any number of properties as keyword arguments when creating an instance of a widget. To create a label aligned to the right with the text “Hello World” and an angle of 25 degrees, use:
label = Gtk.Label(label="Hello World", angle=25, halign=Gtk.Align.END)

Instead of using getters and setters widget.get_property("prop-name") respectively.

you and

can also get and set the properties with widget.set_property("prop-name", value),

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CHAPTER

FOUR

HOW TO DEAL WITH STRINGS
This section explains how strings are represented in Python 2.x, Python 3.x and GTK+ and discusses common errors that arise when working with strings.

4.1 Deﬁnitions
Conceptionally, a string is a list of characters such as ‘A’, ‘B’, ‘C’ or ‘É’. Characters are abstract representations and their meaning depends on the language and context they are used in. The Unicode standard describes how characters are represented by code points. For example the characters above are represented with the code points U+0041, U+0042, U+0043, and U+00C9, respectively. Basically, code points are numbers in the range from 0 to 0x10FFFF. As mentioned earlier, the representation of a string as a list of code points is abstract. In order to convert this abstract representation into a sequence of bytes the Unicode string must be encoded. The simplest from of encoding is ASCII and is performed as follows: 1. If the code point is < 128, each byte is the same as the value of the code point. 2. If the code point is 128 or greater, the Unicode string can’t be represented in this encoding. (Python raises a UnicodeEncodeError exception in this case.) Although ASCII encoding is simple to apply it can only encode for 128 different characters which is hardly enough. One of the most commonly used encodings that addresses this problem is UTF-8 (it can handle any Unicode code point). UTF stands for “Unicode Transformation Format”, and the ‘8’ means that 8-bit numbers are used in the encoding.

4.2 Python 2
4.2.1 Python 2.x’s Unicode Support
Python 2 comes with two different kinds of objects that can be used to represent strings, str and unicode. Instances of the latter are used to express Unicode strings, whereas instances of the str type are byte representations (the encoded string). Under the hood, Python represents Unicode strings as either 16- or 32-bit integers, depending on how the Python interpreter was compiled. Unicode strings can be converted to 8-bit strings with unicode.encode():
>>> unicode_string = u"Fu\u00dfb\u00e4lle" >>> print unicode_string Fußbälle >>> type(unicode_string) <type ’unicode’>

4.2.2 Unicode in GTK+
GTK+ uses UTF-8 encoded strings for all text. This means that if you call a method that returns a string you will always obtain an instance of the str type. The same applies to methods that expect one or more strings as parameter, they must be UTF-8 encoded. However, for convenience PyGObject will automatically convert any unicode instance to str if supplied as argument:

Note the warning at the end. Although we called Gtk.Label.set_text() with a unicode instance as argument, Gtk.Label.get_text() will always return a str instance. Accordingly, txt and unicode_string are not equal. This is especially important if you want to internationalize your program using gettext. You have to make sure that gettext will return UTF-8 encoded 8-bit strings for all languages. In general it is recommended to not use unicode objects in GTK+ applications at all and only use UTF-8 encoded str objects since GTK+ does not fully integrate with unicode objects. Otherwise, you would have to decode the return values to Unicode strings each time you call a GTK+ method:
>>> txt = label.get_text().decode("utf-8") >>> txt == unicode_string True

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4.3 Python 3
4.3.1 Python 3.x’s Unicode support
Since Python 3.0, all strings are stored as Unicode in an instance of the str type. Encoded strings on the other hand are represented as binary data in the form of instances of the bytes type. Conceptionally, str refers to text, whereas bytes refers to data. Use str.encode() to go from str to bytes, and bytes.decode() to go from bytes to str. In addition, it is no longer possible to mix Unicode strings with encoded strings, because it will result in a TypeError:
>>> text = "Fu\u00dfb\u00e4lle" >>> data = b" sind rund" >>> text + data Traceback (most recent call last): File "<stdin>", line 1, in <module> TypeError: Can’t convert ’bytes’ object to str implicitly >>> text + data.decode("utf-8") ’Fußbälle sind rund’ >>> text.encode("utf-8") + data b’Fu\xc3\x9fb\xc3\xa4lle sind rund’

4.4 References
What’s new in Python 3.0 describes the new concepts that clearly distinguish between text and data. The Unicode HOWTO discusses Python 2.x’s support for Unicode, and explains various problems that people commonly encounter when trying to work with Unicode. The Unicode HOWTO for Python 3.x discusses Unicode support in Python 3.x. UTF-8 encoding table and Unicode characters contains a list of Unicode code points and their respective UTF-8 encoding.

4.3. Python 3

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CHAPTER

FIVE

LAYOUT CONTAINERS
While many GUI toolkits require you to precisely place widgets in a window, using absolute positioning, GTK+ uses a different approach. Rather than specifying the position and size of each widget in the window, you can arrange your widgets in rows, columns, and/or tables. The size of your window can be determined automatically, based on the sizes of the widgets it contains. And the sizes of the widgets are, in turn, determined by the amount of text they contain, or the minimum and maximum sizes that you specify, and/or how you have requested that the available space should be shared between sets of widgets. You can perfect your layout by specifying padding distance and centering values for each of your widgets. GTK+ then uses all this information to resize and reposition everything sensibly and smoothly when the user manipulates the window. GTK+ arranges widgets hierarchically, using containers. They are invisible to the end user and are inserted into a window, or placed within each other to layout components. There are two ﬂavours of containers: single-child containers, which are all descendants of Gtk.Bin, and multiple-child containers, which are descendants of Gtk.Container. The most commonly used are vertical or horizontal boxes (Gtk.Box), tables (Gtk.Table) and grids (Gtk.Grid).

5.1 Boxes
Boxes are invisible containers into which we can pack our widgets. When packing widgets into a horizontal box, the objects are inserted horizontally from left to right or right to left depending on whether Gtk.Box.pack_start() or Gtk.Box.pack_end() is used. In a vertical box, widgets are packed from top to bottom or vice versa. You may use any combination of boxes inside or beside other boxes to create the desired effect.

5.1.1 Box Objects
class Gtk.Box([homogenous[, spacing ]]) The rectangular area of a Gtk.Box is organized into either a single row or a single column of child widgets depending upon whether the “orientation” property is set to Gtk.Orientation.HORIZONTAL or Gtk.Orientation.VERTICAL. If homogeneous is True, all widgets in the box will be the same size, of which the size is determined by the largest child widget. If it is omitted, homogeneous defaults to False. spacing is the number of pixels to place by default between children. If omitted, no spacing is used, i.e. spacing is set to 0. By default, child widgets are organized into a single row, i.e. Gtk.Orientation.HORIZONTAL. the “orientation” property is set to

Gtk.Box uses a notion of packing. Packing refers to adding widgets with reference to a particular position in a Gtk.Container. For a Gtk.Box, there are two reference positions: the start and the end of the box. If “orientation” is Gtk.Orientation.VERTICAL, the start is deﬁned as the top of the box and the end is 15

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deﬁned as the bottom. If “orientation” is Gtk.Orientation.HORIZONTAL, the start is deﬁned as the left side and the end is deﬁned as the right side. pack_start(child, expand, ﬁll, padding) Adds child to box, packed with reference to the start of box. The child is packed after any other child packed with reference to the start of box. child should be a Gtk.Widget to be added to this box. The expand argument when set to True allows the child widget to take all available space it can. Alternately, if the value is set to False, the box will be shrunken to the same size as the child widget. If the ﬁll argument is set to True, the child widget takes all available space and is equal to the size of the box. This only has an effect when expand is set to True. A child is always allocated the full height of a horizontally oriented and the full width of a vertically oriented box. This option affects the other dimension. padding deﬁnes extra space in pixels to put between this child and its neighbours, over and above the global amount speciﬁed by “spacing” property. If child is a widget at one of the reference ends of box, then padding pixels are also put between child and the reference edge of this box. pack_end(child, expand, ﬁll, padding) Adds child to box, packed with reference to the end of box. The child is packed after (away from end of) any other child packed with reference to the end of box. Arguments are the same as for pack_start(). set_homogeneous(homogeneous) If homogeneous is True, all widgets in the box will be the same size, of which the size is determined by the largest child widget.

5.1.2 Example
Let’s take a look at a slightly modiﬁed version of the extended example with two buttons.

First, we create a horizontally orientated box container where 6 pixels are placed between children. This box becomes the child of the top-level window.
self.box = Gtk.Box(spacing=6) self.add(self.box)

While with Gtk.Box.pack_start() widgets are positioned from left to right, Gtk.Box.pack_end() positions them from right to left.

5.2 Table
Tables allows us to place widgets in a grid similar to Gtk.Grid. The grid’s dimensions need to be speciﬁed in the Gtk.Table constructor. To place a widget into a box, use Gtk.Table.attach(). Gtk.Table.set_row_spacing() and Gtk.Table.set_col_spacing() set the spacing between the rows at the speciﬁed row or column. Note that for columns, the space goes to the right of the column, and for rows, the space goes below the row. You can also set a consistent spacing for all rows and/or columns with Gtk.Table.set_row_spacings() and Gtk.Table.set_col_spacings(). Note that with these calls, the last row and last column do not get any spacing.

5.2.1 Table Objects
class Gtk.Table(rows, columns, homogeneous) The ﬁrst argument is the number of rows to make in the table, while the second, obviously, is the number of columns. If homogeneous is True, the table cells will all be the same size (the size of the largest widget in the table). attach(child, left_attach, right_attach, top_attach, bottom_attach[, xoptions[, yoptions[, xpadding[, ypadding ]]]]) Adds a widget to a table.

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child is the widget that should be added to the table. The number of ‘cells’ that a widget will occupy is speciﬁed by left_attach, right_attach, top_attach and bottom_attach. These each represent the leftmost, rightmost, uppermost and lowest column and row numbers of the table. (Columns and rows are indexed from zero). For example, if you want a button in the lower-right cell of a 2 x 2 table, and want it to occupy that cell only, then the code looks like the following.
button = Gtk.Button() table = Gtk.Table(2, 2, True) table.attach(button, 1, 2, 1, 2)

If, on the other hand, you wanted a widget to take up the entire top row of our 2 x 2 table, you’d use
table.attach(button, 0, 2, 0, 1)

xoptions and yoptions are used to specify packing options and may be bitwise ORed together to allow multiple options. These options are: •Gtk.AttachOptions.EXPAND: The widget should expand to take up any extra space in its container that has been allocated. •Gtk.AttachOptions.FILL: The widget will expand to use all the room available. •Gtk.AttachOptions.SHRINK: Reduce size allocated to the widget to prevent it from moving off screen. If omitted, xoptions and Gtk.AttachOptions.FILL. yoptions defaults to Gtk.AttachOptions.EXPAND |

Finally, the padding arguments work just as they do for Gtk.Box.pack_start(). If omitted, xpadding and ypadding defaults to 0. set_row_spacing(row, spacing) Changes the space between a given table row and the subsequent row. set_col_spacing(col, spacing) Alters the amount of space between a given table column and the following column. set_row_spacings(spacing) Sets the space between every row in this table equal to spacing. set_col_spacings(spacing) Sets the space between every column in this table equal to spacing.

5.3 Grid
Gtk.Grid is a container which arranges its child widgets in rows and columns, but you do not need to specify the dimensions in the constructor. Children are added using Gtk.Grid.attach(). They can span multiple rows or columns. It is also possible to add a child next to an existing child, using Gtk.Grid.attach_next_to(). Gtk.Grid can be used like a Gtk.Box by just using Gtk.Grid.add(), which will place children next to each other in the direction determined by the “orientation” property (defaults to Gtk.Orientation.HORIZONTAL).

5.3.1 Grid Objects
class Gtk.Grid Creates a new grid widget. attach(child, left, top, width, height) Adds child to this grid. The position of child is determined by the index of the cell left to it (left) and above of it (top). The number of ‘cells’ that child will occupy is determined by width and height. attach_next_to(child, sibling, side, width, height) Adds child to this grid, next to sibling. side is the side of sibling that child is positioned next to. It can be one of •Gtk.PositionType.LEFT •Gtk.PositionType.RIGHT

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•Gtk.PositionType.TOP •Gtk.PositionType.BOTTOM width and height determine the number of ‘cells’ that child will occupy. add(widget) Adds widget to this grid in the direction determined by the “orientation” property.

LABEL
Labels are the main method of placing non-editable text in windows, for instance to place a title next to a Gtk.Entry widget. You can specify the text in the constructor, or later with the Gtk.Label.set_text() or Gtk.Label.set_markup() methods. The width of the label will be adjusted automatically. You can produce multi-line labels by putting line breaks (“\n”) in the label string. Labels can be made selectable with Gtk.Label.set_selectable(). Selectable labels allow the user to copy the label contents to the clipboard. Only labels that contain useful-to-copy information — such as error messages — should be made selectable. The label text can be justiﬁed using the Gtk.Label.set_justify() method. The widget is also capable of word-wrapping, which can be activated with Gtk.Label.set_line_wrap(). Gtk.Label support some simple formatting, for instance allowing you to make some text bold, colored, or larger. You can do this by providing a string to Gtk.Label.set_markup(), using the Pango Markup syntax 1 . For instance, <b>bold text</b> and <s>strikethrough text</s>. In addition, Gtk.Label supports clickable hyperlinks. The markup for links is borrowed from HTML, using the a with href and title attributes. GTK+ renders links similar to the way they appear in web browsers, with colored, underlined text. The title attribute is displayed as a tooltip on the link.

Labels may contain mnemonics. Mnemonics are underlined characters in the label, used for keyboard navigation. Mnemonics are created by providing a string with an underscore before the mnemonic character, such as “_File”, to the functions Gtk.Label.new_with_mnemonic() or Gtk.Label.set_text_with_mnemonic(). Mnemonics automatically activate any activatable widget the label is inside, such as a Gtk.Button; if the label is not inside the mnemonic’s target widget, you have to tell the label about the target using Gtk.Label.set_mnemonic_widget().

6.1 Label Objects
class Gtk.Label([text ]) Creates a new label with the given text inside it. If text is omitted, an empty label is created. static new_with_mnemonic(text) Creates a new label with text inside it. If characters in text are preceded by an underscore, they are underlined. If you need a literal underscore character in a label, use ‘__’ (two underscores). The ﬁrst underlined character represents a keyboard accelerator called a
1

mnemonic. The mnemonic key can be used to activate another widget, chosen automatically, or explicitly using Gtk.Label.set_mnemonic_widget(). If Gtk.Label.set_mnemonic_widget() is not called, then the ﬁrst activatable ancestor of the Gtk.Label will be chosen as the mnemonic widget. For instance, if the label is inside a button or menu item, the button or menu item will automatically become the mnemonic widget and be activated by the mnemonic. set_justify(justiﬁcation) Sets the alignment of the lines in the text of the label relative to each other. justiﬁcation can be one of Gtk.Justification.LEFT, Gtk.Justification.RIGHT, Gtk.Justification.CENTER, Gtk.Justification.FILL. This method has no effect on labels containing only a single line. set_line_wrap(wrap) If wrap is True, lines will be broken if text exceeds the widget’s size. If wrap is False, text will be cut off by the edge of the widget if it exceeds the widget size. set_markup(markup) Parses markup which is marked up with the Pango text markup language 1 , setting the label’s text accordingly. The markup passed must be valid; for example literal <, >, & characters must be escaped as &lt; &gt; and &amp. set_mnemonic_widget(widget) If the label has been set so that it has an mnemonic key, the label can be associated with a widget that is the target of the mnemonic. set_selectable(selectable) Selectable labels allow the user to select text from the label, for copy-and-paste. set_text(text) Sets the text within this widget. It overwrites any text that was there before. set_text_with_mnemonic(text) See new_with_mnemonic().

ENTRY
Entry widgets allow the user to enter text. You can change the contents with the Gtk.Entry.set_text() method, and read the current contents with the Gtk.Entry.get_text() method. You can also limit the number of characters the Entry can take by calling Gtk.Entry.set_max_length(). Occasionally you might want to make an Entry widget read-only. This can be done by passing False to the Gtk.Entry.set_editable() method. Entry widgets can also be used to retrieve passwords from the user. It is common practice to hide the characters typed into the entry to prevent revealing the password to a third party. Calling Gtk.Entry.set_visibility() with False will cause the text to be hidden. Gtk.Entry has the ability to display progress or activity information behind the text. This is similar to Gtk.ProgressBar widget and is commonly found in web browsers to indicate how much of a page download has been completed. To make an entry display such information, use Gtk.Entry.set_progress_fraction(), Gtk.Entry.set_progress_pulse_step(), or Gtk.Entry.progress_pulse(). Additionally, an Entry can show icons at either side of the entry. These icons can be activatable by clicking, can be set up as drag source and can have tooltips. To add an icon, use Gtk.Entry.set_icon_from_stock() or one of the various other functions that set an icon from an icon name, a pixbuf, or icon theme. To set a tooltip on an icon, use Gtk.Entry.set_icon_tooltip_text() or the corresponding function for markup.

7.1 Entry Objects
class Gtk.Entry get_text() Retrieves the contents of the entry widget. set_text(text) Sets the text in the widget to the given value, replacing the current contents. set_visibility(visible) Sets whether the contents of the entry are visible or not. When visible is set to False, characters are displayed as the invisible char, and will also appear that way when the text in the entry widget is copied elsewhere. set_max_length(max) Sets the maximum allowed length of the contents of the widget. If the current contents are longer than the given length, then they will be truncated to ﬁt.

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set_editable(is_editable) Determines if the user can edit the text in the editable widget or not. If is_editable is True, the user is allowed to edit the text in the widget. set_progress_fraction(fraction) Causes the entry’s progress indicator to “ﬁll in” the given fraction of the bar. The fraction should be between 0.0 and 1.0, inclusive. set_progress_pulse_step(fraction) Sets the fraction of total entry width to move the progress bouncing block for each call to progress_pulse(). progress_pulse() Indicates that some progress is made, but you don’t know how much. Causes the entry’s progress indicator to enter “activity mode,” where a block bounces back and forth. Each call to progress_pulse() causes the block to move by a little bit (the amount of movement per pulse is determined by set_progress_pulse_step()). set_icon_from_stock(icon_pos, stock_id) Sets the icon shown in the entry at the speciﬁed position from a stock item. If stock_id is None, no icon will be shown in the speciﬁed position. icon_pos speciﬁes the side of the entry at which an icon is placed and can be one of •Gtk.EntryIconPosition.PRIMARY: At the beginning of the entry (depending on the text direction). •Gtk.EntryIconPosition.SECONDARY: At the end of the entry (depending on the text direction). set_icon_tooltip_text(icon_pos, tooltip) Sets tooltip as the contents of the tooltip for the icon at the speciﬁed position. If tooltip is None, an existing tooltip is removed. For allowed values for icon_pos see set_icon_from_stock().

BUTTON WIDGETS
8.1 Button
The Button widget is another commonly used widget. It is generally used to attach a function that is called when the button is pressed. The Gtk.Button widget can hold any valid child widget. That is it can hold most any other standard Gtk.Widget. The most commonly used child is the Gtk.Label. Usually, you want to connect to the button’s “clicked” signal which is emitted when the button has been pressed and released.

8.1.1 Button Objects
class Gtk.Button([label[, stock[, use_underline ]]]) If label is not None, creates a new Gtk.Button with a Gtk.Label child containing the given text. If stock is not None, creates a new button containing the image and text from a stock item. If use_underline is set to True, an underline in the text indicates the next character should be used for the mnemonic accelerator key. set_label(label) Sets the text of the label of the button to label. set_use_underline(use_underline) If True, an underline in the text of the button label indicates the next character should be used for the mnemonic accelerator key.

8.2 ToggleButton
A Gtk.ToggleButton is very similar to a normal Gtk.Button, but when clicked they remain activated, or pressed, until clicked again. When the state of the button is changed, the “toggled” signal is emitted. To retrieve the state of the Gtk.ToggleButton, you can use the Gtk.ToggleButton.get_active() method. This returns True if the button is “down”. You can also set the toggle button’s state, with Gtk.ToggleButton.set_active(). Note that, if you do this, and the state actually changes, it causes the “toggled” signal to be emitted.

8.2.1 ToggleButton Objects
class Gtk.ToggleButton([label[, stock[, use_underline ]]]) The arguments are the same as for the Gtk.Button constructor. get_active()

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Returns the buttons current state. Returns True if the toggle button is pressed in and False if it is raised. set_active(is_active) Sets the status of the toggle button. Set to True if you want the button to be pressed in, and False to raise it. This action causes the “toggled” signal to be emitted.

8.3 CheckButton
Gtk.CheckButton inherits from Gtk.ToggleButton. The only real difference between the two is Gtk.CheckButton‘s appearance. A Gtk.CheckButton places a discrete Gtk.ToggleButton next

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to a widget, (usually a Gtk.Label). The “toggled” signal, Gtk.ToggleButton.set_active() and Gtk.ToggleButton.get_active() are inherited.

8.3.1 CheckButton Objects
class Gtk.CheckButton([label[, stock[, use_underline ]]]) Arguments are the same as for Gtk.Button.

8.4 RadioButton
Like checkboxes, radio buttons also inherit from Gtk.ToggleButton, but these work in groups, and only one Gtk.RadioButton in a group can be selected at any one time. Therefore, a Gtk.RadioButton is one way of giving the user a choice from many options.

Radio buttons can be created with one of the static methods Gtk.RadioButton.new_from_widget(), Gtk.RadioButton.new_with_label_from_widget() or Gtk.RadioButton.new_with_mnemonic_from_widget The ﬁrst radio button in a group will be created passing None as the group argument. In subsequent calls, the group you wish to add this button to should be passed as an argument. When ﬁrst run, the ﬁrst radio button in the group will be active. Gtk.ToggleButton.set_active() with True as ﬁrst argument. Changing a Gtk.RadioButton‘s widget Gtk.RadioButton.join_group(). group after its creation This can be changed by calling can be achieved by calling

8.4.1 RadioButton Objects
class Gtk.RadioButton static new_from_widget(group) Creates a new Gtk.RadioButton, adding it to the same group as the group widget. If group is None, a new group is created. static new_with_label_from_widget(group, label) Creates a new Gtk.RadioButton. The text of the label widget inside the button will be set to label. group is the same as for new_from_widget(). static new_with_mnemonic_from_widget(group, label) Same as new_with_label_from_widget(), but underscores in label indicate the mnemonic for the button. join_group(group) Joins this radio button to the group of another Gtk.RadioButton object.

8.5 LinkButton
A Gtk.LinkButton is a Gtk.Button with a hyperlink, similar to the one used by web browsers, which triggers an action when clicked. It is useful to show quick links to resources. The URI bound to a Gtk.LinkButton can be set speciﬁcally using Gtk.LinkButton.set_uri(), and retrieved using Gtk.LinkButton.get_uri().

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8.5.1 LinkButton Objects
class Gtk.LinkButton(uri[, label ]) uri is the address of the website which should be loaded. The label is set as the text which should be displayed. If it is set to None or omitted, the web address will be displayed instead. get_uri() Retrieves the URI set using set_uri(). set_uri(uri) Sets uri as the URI where this button points to. As a side-effect this unsets the ‘visited’ state of the button.

8.6 SpinButton
A Gtk.SpinButton is an ideal way to allow the user to set the value of some attribute. Rather than having to directly type a number into a Gtk.Entry, Gtk.SpinButton allows the user to click on one of two arrows to increment or decrement the displayed value. A value can still be typed in, with the bonus that it can be checked to ensure it is in a given range. The main properties of a Gtk.SpinButton are set through Gtk.Adjustment. To change the value that Gtk.SpinButton is showing, use Gtk.SpinButton.set_value(). The value entered can either be an integer or ﬂoat, depending on your requirements, use Gtk.SpinButton.get_value() or Gtk.SpinButton.get_value_as_int(), respectively. When you allow the displaying of ﬂoat values in the spin button, you may wish to adjust the number of decimal spaces displayed by calling Gtk.SpinButton.set_digits().

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By default, Gtk.SpinButton accepts textual data. If you wish to limit this to numerical values only, call Gtk.SpinButton.set_numeric() with True as argument. We can also adjust the update policy of Gtk.SpinButton. There are two options here; by default the spin button updates the value even if the data entered is invalid. Alternatively, we can set the policy to only update when the value entered is valid by calling Gtk.SpinButton.set_update_policy().

8.6.1 SpinButton Objects
class Gtk.SpinButton set_adjustment(adjustment) Replaces the Gtk.Adjustment associated with this spin button. set_digits(digits) Set the precision to be displayed by this spin button. Up to 20 digit precision is allowed. set_increments(step, page) Sets the step and page increments for this spin button. This affects how quickly the value changes when the spin button’s arrows are activated. set_value(value) Sets the value of this spin button. get_value() Get the value of this spin button represented as an ﬂoat. get_value_as_int() Get the value of this spin button represented as an integer. set_numeric(numeric) If numeric is False, non-numeric text can be typed into the spin button, else only numbers can be typed. set_update_policy(policy) Sets the update behavior of a spin button. This determines wether the spin button is always updated or only when a valid value is set. The policy argument can either be Gtk.SpinButtonUpdatePolicy.ALWAYS or Gtk.SpinButtonUpdatePolicy.IF_VALID.

8.6.2 Adjustment Objects
class Gtk.Adjustment(value, lower, upper, step_increment, page_increment, page_size) The Gtk.Adjustment object represents a value which has an associated lower and upper bound, together with step and page increments, and a page size. It is used within several GTK+ widgets, including Gtk.SpinButton, Gtk.Viewport, and Gtk.Range. value is the initial value, lower the minimum value, upper the maximum value, step_increment the step increment, page_increment the page increment, and page_size the page size.

PROGRESSBAR
The Gtk.ProgressBar is typically used to display the progress of a long running operation. It provides a visual clue that processing is underway. The Gtk.ProgressBar can be used in two different modes: percentage mode and activity mode. When an application can determine how much work needs to take place (e.g. read a ﬁxed number of bytes from a ﬁle) and can monitor its progress, it can use the Gtk.ProgressBar in percentage mode and the user sees a growing bar indicating the percentage of the work that has been completed. In this mode, the application is required to call Gtk.ProgressBar.set_fraction() periodically to update the progress bar, passing a ﬂoat between 0 and 1 to provide the new percentage value. When an application has no accurate way of knowing the amount of work to do, it can use activity mode, which shows activity by a block moving back and forth within the progress area. In this mode, the application is required to call Gtk.ProgressBar.pulse() periodically to update the progress bar. You can also choose the step size, with the Gtk.ProgressBar.set_pulse_step() method. By default, Gtk.ProgressBar is horizontal and left-to-right, but you can change it to a vertical progress bar by using the Gtk.ProgressBar.set_orientation() method. Changing the direction the progress bar grows can be done using Gtk.ProgressBar.set_inverted(). Gtk.ProgressBar can also contain text which can be set by calling Gtk.ProgressBar.set_text() and Gtk.ProgressBar.set_show_text().

9.1 ProgressBar Objects
class Gtk.ProgressBar set_fraction(fraction) Causes the progress bar to “ﬁll in” the given fraction of the bar. fraction should be between 0.0 and 1.0, inclusive. set_pulse_step(fraction) Sets the fraction of total progress bar length to move the bouncing block for each call to pulse(). pulse() Indicates that some progress is made, but you don’t know how much. Causes the progress bar to enter activity mode, where a block bounces back and forth. Each call to pulse() causes the block to move by a little bit (the amount of movement per pulse is determined by set_pulse_step()). set_orientation(orientation) Sets the orientation. orientation can be one of •Gtk.Orientation.HORIZONTAL •Gtk.Orientation.VERTICAL 39

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set_show_text(show_text) Sets whether the progressbar will show text superimposed over the bar. The shown text is either the value of the “text” property or, if that is None, the “fraction” value, as a percentage. set_text(text) Causes the given text to appear superimposed on the progress bar. set_inverted(inverted) Progress bars normally grow from top to bottom or left to right. Inverted progress bars grow in the opposite direction.

TREE AND LIST WIDGETS
A Gtk.TreeView and its associated widgets are an extremely powerful way of displaying data. They are used in conjunction with a Gtk.ListStore or Gtk.TreeStore and provide a way of displaying and manipulating data in many ways, including: • Automatically updates when data added, removed or edited • Drag and drop support • Sorting of data • Support embedding widgets such as check boxes, progress bars, etc. • Reorderable and resizable columns • Filtering of data With the power and ﬂexibility of a Gtk.TreeView comes complexity. It is often difﬁcult for beginner developers to be able to utilize correctly due to the number of methods which are required.

10.1 The Model
Each Gtk.TreeView has an associated Gtk.TreeModel, which contains the data displayed by the TreeView. Each Gtk.TreeModel can be used by more than one Gtk.TreeView. For instance, this allows the same underlying data to be displayed and edited in 2 different ways at the same time. Or the 2 Views might display different columns from the same Model data, in the same way that 2 SQL queries (or “views”) might show different ﬁelds from the same database table. Although you can theoretically implement your own Model, you will normally use either the Gtk.ListStore or Gtk.TreeStore model classes. Gtk.ListStore contains simple rows of data, and each row has no children, whereas Gtk.TreeStore contains rows of data, and each row may have child rows. When constructing a model you have to specify the data types for each column the model holds.
store = Gtk.ListStore(str, str, float)

This creates a list store with three columns, two string columns, and a ﬂoat column. Adding data to the model is done using Gtk.ListStore.append() or Gtk.TreeStore.append(), depending upon which sort of model was created.
treeiter = store.append(["The Art of Computer Programming", "Donald E. Knuth", 25.46])

Both methods return a Gtk.TreeIter instance, which points to the location of the newly inserted row. You can retrieve a Gtk.TreeIter by calling Gtk.TreeModel.get_iter().

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Once, data has been inserted you can retrieve or modify data using the tree iter and column index.
print store[treeiter][2] # Prints value of third column store[treeiter][2] = 42.15

As with Python’s built-in list object you can use len() to get the number of rows and use slices to retrieve or set values.
# Print number of rows print len(store) # Print all but first column print store[treeiter][1:] # Print last column print store[treeiter][-1] # Set first two columns store[treeiter][:2] = ["Donald Ervin Knuth", 41.99]

Iterating over all rows of a tree model is very simple as well.
for row in store: # Print values of all columns print row[:]

Keep in mind, that if you use Gtk.TreeStore, the above code will only iterate over the rows of the top level, but not the children of the nodes. To iterate over all rows and its children, use the print_tree_store function.
def print_tree_store(store): rootiter = store.get_iter_first() print_rows(store, rootiter, "") def print_rows(store, treeiter, indent): while treeiter != None: print indent + str(store[treeiter][:]) if store.iter_has_child(treeiter): childiter = store.iter_children(treeiter) print_rows(store, childiter, indent + "\t") treeiter = store.iter_next(treeiter)

Apart from accessing values stored in a Gtk.TreeModel with the list-like method mentioned above, it is also possible to either use Gtk.TreeIter or Gtk.TreePath instances. Both reference a particular row in a tree model. One can convert a path to an iterator by calling Gtk.TreeModel.get_iter(). As Gtk.ListStore contains only one level, i.e. nodes do not have any child nodes, a path is essentially the index of the row you want to access.
# Get path pointing to 6th row in list store path = Gtk.TreePath(5) treeiter = liststore.get_iter(path) # Get value at 2nd column value = liststore.get_value(treeiter, 1)

In the case of Gtk.TreeStore, a path is a list of indexes or a string. The string form is a list of numbers separated by a colon. Each number refers to the offset at that level. Thus, the path “0” refers to the root node and the path “2:4” refers to the ﬁfth child of the third node.
# Get path pointing to 5th child of 3rd row in tree store path = Gtk.TreePath([2, 4]) treeiter = treestore.get_iter(path) # Get value at 2nd column value = treestore.get_value(treeiter, 1)

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10.1.1 TreeModel Objects
class Gtk.TreeModel get_iter(path) Returns a Gtk.TreeIter instance pointing to path. path is expected to be a colon separated list of numbers or a tuple. For example, the string “10:4:0” or tuple (10, 4, 0) would create a path of depth 3 pointing to the 11th child of the root node, the 5th child of that 11th child, and the 1st child of that 5th child. iter_next(treeiter) Returns a Gtk.TreeIter instance pointing the node following treeiter at the current level or None if there is no next iter. iter_has_child(treeiter) Returns True if treeiter has children, False otherwise. iter_children(treeiter) Returns a Gtk.TreeIter instance pointing to the ﬁrst child of treeiter or None if treeiter has no children. get_iter_first() Returns a Gtk.TreeIter instance pointing to the ﬁrst iterator in the tree (the one at the path “0”) or None if the tree is empty.

10.1.2 ListStore Objects
class Gtk.ListStore(data_type[, ... ]) Creates a new Gtk.ListStore with the speciﬁed column data types. Each row added to the list store will have an item in each column. Supported data types are the standard Python ones and GTK+ types: •str, int, ﬂoat, long, bool, object •GObject.GObject append([row ]) Appends a new row to this list store. row is a list of values for each column, i.e. len(store) == len(row). If row is omitted or None, an empty row will be appended. Returns a Gtk.TreeIter pointing to the appended row.

10.1.3 TreeStore Objects
class Gtk.TreeStore(data_type[, ... ]) Arguments are the same as for the Gtk.ListStore constructor. append(parent[, row ]) Appends a new row to this tree store. parent must be a valid Gtk.TreeIter. If parent is not None, then it will append the new row after the last child of parent, otherwise it will append a row to the top level. row is a list of values for each column, i.e. len(store) == len(row). If row is omitted or None, an empty row will be appended. 10.1. The Model 45

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Returns a Gtk.TreeIter pointing to the appended row.

10.1.4 TreePath Objects
class Gtk.TreePath(path) Construct a Gtk.TreePath pointing to the node speciﬁed by path. If path is a string it is expected to be a colon separated list of numbers. For example, the string “10:4:0” would create a path of depth 3 pointing to the 11th child of the root node, the 5th child of that 11th child, and the 1st child of that 5th child. If path is a list or a tuple it is expected to contain the indexes of the nodes. Referring to the above mentioned example, the expression Gtk.TreePath("10:4:0") is equivalent to Gtk.TreePath([10, 4, 3]).

10.2 The View
While there are several different models to choose from, there is only one view widget to deal with. It works with either the list or the tree store. Setting up a Gtk.TreeView is not a difﬁcult matter. It needs a Gtk.TreeModel to know where to retrieve its data from, either by passing it to the Gtk.TreeView constructor, or by calling Gtk.TreeView.set_model().
tree = Gtk.TreeView(store)

Once the Gtk.TreeView widget has a model, it will need to know how to display the model. It does this with columns and cell renderers. Cell renderers are used to draw the data in the tree model in a way. There are a number of cell renderers that come with GTK+, for instance Gtk.CellRendererText, Gtk.CellRendererPixbuf and Gtk.CellRendererToggle. In addition, it is relatively easy to write a custom renderer yourself. A Gtk.TreeViewColumn is the object that Gtk.TreeView uses to organize the vertical columns in the tree view. It needs to know the name of the column to label for the user, what type of cell renderer to use, and which piece of data to retrieve from the model for a given row.
renderer = Gtk.CellRendererText() column = Gtk.TreeViewColumn("Title", renderer, text=0) tree.append_column(column)

To render more than one model column in a view column, you need to create a Gtk.TreeViewColumn instance and use Gtk.TreeViewColumn.pack_start() to add the model columns to it.
column = Gtk.TreeViewColumn("Title and Author") title = Gtk.CellRendererText() author = Gtk.CellRendererText() column.pack_start(title, True) column.pack_start(author, True) column.add_attribute(title, "text", 0) column.add_attribute(author, "text", 1) tree.append_column(column)

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10.2.1 TreeView Objects
class Gtk.TreeView([treemodel ]) Creates a new Gtk.TreeView widget with the model initialized to treemodel. treemodel must be a class implementing Gtk.TreeModel, such as Gtk.ListStore or Gtk.TreeStore. If treemodel is omitted or None, the model remains unset and you have to call set_model() later. set_model(model) Sets the model for this tree view. If this tree view already has a model set, it will remove it before setting the new model. If model is None, then it will unset the old model. get_model() Returns the model this tree view is based on. Returns None if the model is unset. append_column(column) Appends column to the list of columns. get_selection() Gets the Gtk.TreeSelection associated with this tree view. enable_model_drag_source(start_button_mask, targets, actions) Arguments are the same as Gtk.Widget.drag_source_set() enable_model_dest_source(targets, actions) Arguments are the same as Gtk.Widget.drag_dest_set()

10.2.2 TreeViewColumn Objects
class Gtk.TreeViewColumn(label[, renderer[, **kwargs ]]) Creates a new Gtk.TreeViewColumn. renderer is expected to be a Gtk.CellRenderer instance, and kwargs key-value pairs specifying the default values of renderer‘s properties. This is equivalent to calling pack_start() and add_attribute() for each key-value pair in kwargs. If renderer is omitted, you have to call pack_start() or pack_end() yourself. add_attribute(renderer, attribute, value) Adds an attribute mapping to this column. attribute is the parameter on renderer to be set from the value. So for example if column 2 of the model contains strings, you could have the “text” attribute of a Gtk.CellRendererText get its values from column 2. pack_start(renderer, expand) Packs the renderer into the beginning of this column. If expand is False, then the renderer is allocated no more space than it needs. Any unused space is divided evenly between cells for which expand is True. pack_end(renderer, expand) Adds the renderer to end of this column. If expand is False, then the renderer is allocated no more space than it needs. Any unused space is divided evenly between cells for which expand is True. set_sort_column_id(sort_column_id) Sets the column of the model by which this column (of the view) should be sorted. This also makes the columnd header clickable. get_sort_column_id() Gets the column id set by Gtk.TreeViewColumn.set_sort_column_id()

10.2. The View

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set_sort_indicator(setting) Sets whether a little arrow is displayed in the column header to in setting can either be True (indicator is shown) or False get_sort_indicator() Gets the value set by Gtk.TreeViewColumn.set_sort_indicator() set_sort_order(order) Changes the order by which the column is sorted. order can either be Gtk.SortType.ASCENDING or Gtk.SortType.DESCENDING. get_sort_order() Gets the sort order set by Gtk.TreeViewColumn.set_sort_order()

10.3 The Selection
Most applications will need to not only deal with displaying data, but also receiving input events from users. To do this, simply get a reference to a selection object and connect to the “changed” signal.
select = tree.get_selection() select.connect("changed", on_tree_selection_changed)

You can control what selections are allowed by calling Gtk.TreeSelection.set_mode(). Gtk.TreeSelection.get_selected() does not work if the selection mode is set to Gtk.SelectionMode.MULTIPLE, use Gtk.TreeSelection.get_selected_rows() instead.

10.3.1 TreeSelection Objects
class Gtk.TreeSelection set_mode(type) Where type is one of •Gtk.SelectionMode.NONE: No selection is possible •Gtk.SelectionMode.SINGLE: Zero or one element may be selected •Gtk.SelectionMode.BROWSE: Exactly one element is selected. In some circumstances, such as initially or during a search operation, it’s possible for no element to be selected. What is really enforced is that the user can’t deselect a currently selected element except by selecting another element. •Gtk.SelectionMode.MULTIPLE: Any number of elements may be selected. Clicks toggle the state of an item. Any number of elements may be selected. The Ctrl key may be used to enlarge the selection, and Shift key to select between the focus and the child pointed to. Some widgets may also allow Click-drag to select a range of elements.

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get_selected() Returns a tuple (model, treeiter), where model is the current model and treeiter a Gtk.TreeIter pointing to the currently selected row. treeiter is None if no rows are selected. This function will not work if the mode of this selection is Gtk.SelectionMode.MULTIPLE. get_selected_rows() Returns a list of Gtk.TreePath instances of all selected rows.

10.4 Sorting
Sorting is an important feature for tree views and is supported by the standard tree models (Gtk.TreeStore and Gtk.ListStore), which implement the Gtk.TreeSortable interface.

10.4.1 Sorting by clicking on columns
A column of a Gtk.TreeView can easily made sortable with a call to Gtk.TreeViewColumn.set_sort_column_id(). Afterwards the column can be sorted by clicking on its header. First we need a simple Gtk.TreeView and a Gtk.ListStore as a model.
model = Gtk.ListStore(str) model.append(["Benjamin"]) model.append(["Charles"]) model.append(["alfred"]) model.append(["Alfred"]) model.append(["David"]) model.append(["charles"]) model.append(["david"]) model.append(["benjamin"]) treeView = Gtk.TreeView(model) cellRenderer = Gtk.CellRendererText() column = Gtk.TreeViewColumn("Title", renderer, text=0)

The next step is to enable sorting. Note that the column_id (0 in the example) refers to the column of the model and not to the TreeView’s column.
column.set_sort_column_id(0)

10.4.2 Setting a custom sort function
It is also possible to set a custom comparison function in order to change the sorting behaviour. As an example we will create a comparison function that sorts case-sensitive. In the example above the sorted list looked like:
alfred Alfred benjamin Benjamin charles Charles david David

First of all a comparison function is needed. This function gets two rows and has to return a negative integer if the ﬁrst one should come before the second one, zero if they are equal and a positive integer if the second one should come before the second one.
def compare(model, row1, row2, user_data): sort_column, _ = model.get_sort_column_id() value1 = model.get_value(row1, sort_column) value2 = model.get_value(row2, sort_column) if value1 < value2: return -1 elif value1 == value2: return 0 else: return 1

Then the sort function has to be set by Gtk.TreeSortable.set_sort_func().
model.set_sort_func(0, compare, None)

10.4.3 TreeSortable objects
class Gtk.TreeSortable set_sort_column_id(sort_column_id, order) Sets the current sort column to sort_column_id. order can either be Gtk.SortType.ASCENDING or Gtk.SortType.DESCENDING. get_sort_column_id() Returns a tuple consisting of the current sort column and order. set_sort_func(sort_column_id, sort_func, user_data) Sets the comparison function used when sorting by the colum sort_column_id. user_data gets passed to sort_func. sort_func is a function with the signature sort_func(model, iter1, iter2, user_data) and should return a negative integer if iter1 sorts before iter2, zero if they are equal and a positive integer if iter2 sorts before iter1. set_default_sort_func(sort_func, user_data) See Gtk.TreeSortable.set_sort_func(). This sets the comparison function that is used when sorting by the default sort column

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ELEVEN

CELLRENDERERS
Gtk.CellRenderer widgets are used to display information within widgets such as the Gtk.TreeView or Gtk.ComboBox. They work closely with the associated widgets and are very powerful, with lots of conﬁguration options for displaying a large amount of data in different ways. There are seven Gtk.CellRenderer widgets which can be used for different purposes: • Gtk.CellRendererText • Gtk.CellRendererToggle • Gtk.CellRendererPixbuf • Gtk.CellRendererCombo • Gtk.CellRendererProgress • Gtk.CellRendererSpinner • Gtk.CellRendererSpin • Gtk.CellRendererAccel

11.1 CellRendererText
A Gtk.CellRendererText renders a given text in its cell, using the font, color and style information provided by its properties. The text will be ellipsized if it is too long and the “ellipsize” property allows it. By default, text in Gtk.CellRendererText widgets is not editable. This can be changed by setting the value of the “editable” property to True:
cell.set_property("editable", True)

You can then connect to the “edited” signal and update your Gtk.TreeModel accordingly.

11.1.1 CellRendererText Objects
class Gtk.CellRendererText Creates a new Gtk.CellRendererText instance. Adjust how text is drawn using object properties. Also, with Gtk.TreeViewColumn, you can bind a property to a value in a GtkTreeModel. For example, you can bind the “text” property on the cell renderer to a string value in the model, thus rendering a different string in each row of the Gtk.TreeView.

11.2 CellRendererToggle
Gtk.CellRendererToggle renders a toggle button in a cell. The button is drawn as a radio- or checkbutton, depending on the “radio” property. When activated, it emits the “toggled” signal. As a Gtk.CellRendererToggle can have two states, active and not active, you most likely want to bind the “active” property on the cell renderer to a boolean value in the model, thus causing the check button to reﬂect the state of the model.

11.2.1 CellRendererToggle Objects
class Gtk.CellRendererToggle Creates a new Gtk.CellRendererToggle instance. set_active(setting) Activates or deactivates a cell renderer. get_active() Returns whether the cell renderer is active. set_radio(radio) If radio is True, the cell renderer renders a radio toggle (i.e. a toggle in a group of mutually-exclusive toggles). If False, it renders a check toggle (a standalone boolean option). get_radio() Returns whether we’re rendering radio toggles rather than checkboxes.

11.3 CellRendererPixbuf
A Gtk.CellRendererPixbuf can be used to render an image in a cell. It allows to render either a given Gdk.Pixbuf (set via the “pixbuf” property) or a stock item (set via the “stock-id” property).

11.3.1 CellRendererPixbuf Objects
class Gtk.CellRendererPixbuf Creates a new Gtk.CellRendererPixbuf. Adjust rendering parameters using object properties. For example, you can bind the “pixbuf” or “stock-id” property on the cell renderer to a pixbuf value in the model, thus rendering a different image in each row of the Gtk.TreeView.

11.4 CellRendererCombo
Gtk.CellRendererCombo renders text in a cell like Gtk.CellRendererText from which it is derived. But while the latter offers a simple entry to edit the text, Gtk.CellRendererCombo offers a Gtk.ComboBox widget to edit the text. The values to display in the combo box are taken from the Gtk.TreeModel speciﬁed in the “model” property. The combo cell renderer takes care of adding a text cell renderer to the combo box and sets it to display the column speciﬁed by its “text-column” property. A Gtk.CellRendererCombo can operate in two modes. It can be used with and without an associated Gtk.Entry widget, depending on the value of the “has-entry” property.

11.4.1 CellRendererCombo Objects
class Gtk.CellRendererCombo Creates a new Gtk.CellRendererCombo. Adjust how text is drawn using object properties. For example, you can bind the “text” property on the cell renderer to a string value in the model, thus rendering a different string in each row of the Gtk.TreeView.

11.5 CellRendererProgress
Gtk.CellRendererProgress renders a numeric value as a progress bar in a cell. Additionally, it can display a text on top of the progress bar. The percentage value of the progress bar can be modiﬁed by changing the “value” property. Similar to Gtk.ProgressBar, you can enable the activity mode by incrementing the “pulse” property instead of the “value” property.

11.6 CellRendererSpin
Gtk.CellRendererSpin renders text in a cell like Gtk.CellRendererText from which it is derived. But while the latter offers a simple entry to edit the text, Gtk.CellRendererSpin offers a Gtk.SpinButton widget. Of course, that means that the text has to be parseable as a ﬂoating point number. The range of the spinbutton is taken from the adjustment property of the cell renderer, which can be set explicitly or mapped to a column in the tree model, like all properties of cell renders. Gtk.CellRendererSpin also has properties for the climb rate and the number of digits to display.

COMBOBOX
A Gtk.ComboBox allows for the selection of an item from a dropdown menu. They are preferable to having many radio buttons on screen as they take up less room. If appropriate, it can show extra information about each item, such as text, a picture, a checkbox, or a progress bar. Gtk.ComboBox is very similar to Gtk.TreeView, as both use the model-view pattern; the list of valid choices is speciﬁed in the form of a tree model, and the display of the choices can be adapted to the data in the model by using cell renderers. If the combo box contains a large number of items, it may be better to display them in a grid rather than a list. This can be done by calling Gtk.ComboBox.set_wrap_width(). The Gtk.ComboBox widget usually restricts the user to the available choices, but it can optionally have an Gtk.Entry, allowing the user to enter arbitrary text if none of the available choices are suitable. To do this, use one of the static methods Gtk.ComboBox.new_with_entry() or Gtk.ComboBox.new_with_model_and_entry() to create an Gtk.ComboBox instance. For a simple list of textual choices, the model-view API of Gtk.ComboBox can be a bit overwhelming. In this case, Gtk.ComboBoxText offers a simple alternative. Both Gtk.ComboBox and Gtk.ComboBoxText can contain an entry.

12.1 ComboBox objects
class Gtk.ComboBox static new_with_entry() Creates a new empty Gtk.ComboBox with an entry. static new_with_model(model) Creates a new Gtk.ComboBox with the model initialized to model. static new_with_model_and_entry(model) Creates a new Gtk.ComboBox with an entry and the model initialized to model. get_active_iter() Returns a Gtk.TreeIter pointing to the current active item. If no active item exists, None is returned. set_model(model) Sets the model used by this combo box to be model. Will unset a previously set model (if applicable). If model is None, then it will unset the model. Note that this function does not clear the cell renderers. get_model() Returns the Gtk.TreeModel which is acting as data source for this combo box.

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set_entry_text_column(text_column) Sets the model column which this combo box should use to get strings from to be text_column. The column text_column in the model of this combo box must be of type str. This is only relevant if this combo box has been created with the “has-entry” property set to True. set_wrap_width(width) Sets the wrap width of this combo box to be width. The wrap width is basically the preferred number of columns when you want the popup to be layed out in a grid.

12.2 ComboBoxText objects
class Gtk.ComboBoxText static new_with_entry() Creates a new empty Gtk.ComboBoxText with an entry. append_text(text) Appends text to the list of strings stored in this combo box. get_active_text() Returns the currently active string in this combo box, or None if none is selected. If this combo box contains an entry, this function will return its contents (which will not necessarily be an item from the list).

ICONVIEW
A Gtk.IconView is a widget that displays a collection of icons in a grid view. It supports features such as drag and drop, multiple selections and item reordering. Similarly to Gtk.TreeView, Gtk.IconView uses a Gtk.ListStore for its model. Instead of using cell renderers, Gtk.IconView requires that one of the columns in its Gtk.ListStore contains GdkPixbuf.Pixbuf objects. Gtk.IconView supports numerous selection modes to allow for either selecting multiple icons at a time, restricting selections to just one item or disallowing selecting items completely. To specify a selection mode, the Gtk.IconView.set_selection_mode() method is used with one of the Gtk.SelectionMode selection modes.

13.1 IconView objects
class Gtk.IconView static new_with_area(area) Creates a new Gtk.IconView widget using the speciﬁed area to layout cells inside the icons. static new_with_model(model) Creates a new Gtk.IconView widget with the model model. set_model(model) Sets the model for a Gtk.IconView. If the Gtk.IconView already has a model set, it will remove it before setting the new model. If model is None, then it will unset the old model. get_model() Returns the model the Gtk.IconView is based on. Returns None if the model is unset. set_text_column(column) Sets the column with text to be column. The text column must be of type str. get_text_column() Return the column with text, or -1 if it’s unset. set_markup_column(column) Sets the column with markup information for the Gtk.IconView to be column. The markup column must be of type str. If the markup column is set to something, it overrides the text column set by set_text_column(). get_markup_column() Returns the column with markup text, or -1 if it’s unset.

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set_pixbuf_column(column) Sets the column with pixbufs to be column. The pixbuf column must be of type GdkPixbuf.Pixbuf get_pixbuf_column() Returns the column with pixbufs, or -1 if it’s unset. get_item_at_pos(x, y) Finds the path at the point(x, y), relative to bin_window coordinates. In contrast to get_path_at_pos(), this method also obtains the cell at the speciﬁed position. See convert_widget_to_bin_window_coords() for converting widget coordinates to bin_window coordinates. convert_widget_to_bin_coords(x, y) Converts widget coordinates to coordinates get_path_at_pos() for the bin_window, as expected by e.g.

set_cursor(path, cell, start_editing) Sets the current keyboard focus to be at path, and selects it. This is useful when you want to focus the user’s attention on a particular item. If cell is None, then focus is given to the cel speciﬁed by it. Additionally, if start_editing is True, then editing should be started in the speciﬁed cell. This function is often followed by grab_focus() in order to give keyboard focus to the widget. Please note that editing can only happen when the widget is realized. get_cursor() Returns the current cursor path and cell. If the cursor isn’t currently set, then path will be None. If no cell currently has focus, then cell will be None. selected_foreach(func, data) Calls a function for each selected icon. Note that the model or selection cannot be modiﬁed from within this method. set_selection_mode(mode) Sets the Gtk.SelectionMode of the Gtk.IconView. get_selection_mode() Gets the Gtk.SelectionMode of the Gtk.IconView. set_item_orientation(orientation) Sets the “item-orientation” property which determines whether the labels are drawn beside the icons instead of below. get_item_orientation() Returns the Gtk.Orientation of the “item-orientation” property which determines whether the labels are drawn beside the icons instead of below. set_columns(columns) Sets the “columns” property which determines in how many columns the icons are arranged. If columns is -1, the number of columns will be chosen automatically to ﬁll the available area. get_columns() Returns the value of the “columns” property. set_item_width(item_width) Sets the “item-width” property which speciﬁes the width to use for each item. If it is set to -1, the icon view will automatically determine a suitable item size. get_item_width() Returns the value of the “item-width” property.

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set_spacing(spacing) Sets the “spacing” property which speciﬁes the space which is inserted between the cells (i.e. the icon and the text) of an item. set_row_spacing(row_spacing) Sets the “row-spacing” property which speciﬁes the space which is inserted between the rows of the icon view. get_row_spacing() Returns the value of the “row-spacing” property. set_column_spacing(column_spacing) Sets the “column-spacing” property which speciﬁes the space which is inserted between the columns of the icon view. get_column_spacing() Returns the value of the “column-spacing” property. set_margin(margin) Sets the “margin” property which speciﬁes the space which is inserted at the top, bottom, left and right of the icon view. get_margin() Returns the value of the “margin” property. set_item_padding(item_padding) Sets the “item-padding” property which speciﬁes the padding around each of the icon view’s items. get_item_padding() Returns the value of the “item-padding property. select_path(path) Selects the row at path. unselect_path(path) Unselects the row at path. path_is_selected(path) Returns True if the icon pointed to by path is currently selected. If path does not point to a valid location, False is returned. get_selected_items() Creates a list of paths of all selected items. Additionally, if you are planning on modifying the model after calling this function, you may want to convert the returned list into a list of Gtk.TreeRowReference. select_all() Selects all the icons. The Gtk.IconView Gtk.SelectionMode.MULTIPLE unselect_all() Unselects all the icons. scroll_to_path(path, use_align, row_align, col_align) Moves the alignments of Gtk.IconView to the position speciﬁed by path. row_align determines where the row is placed, the col_align determines where column is placed. Both are expected to be between 0.0 and 1.0. 0.0 means left/top alignment, 1.0 means right/bottom alignment, 0.5 means center. If use_align is False, the the alignment arguments are ignored, and the tree does the minimum amount of work to scroll the item onto the screen. This means that the item will be scrolled to the edge closest to its current position. If the item is currently visible on the screen, nothing is done. must has its selection mode set to

13.1. IconView objects

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This function only works if the model is set, and path is a valid row on the model. If the model changes before the Gtk.IconView is realized, the centered path will be modiﬁed to reﬂect this change. get_visible_range() Returns the ﬁrst and last visible Gtk.TreePath. Note that there may be invisible paths in between. set_tooltip_item(tooltip, path) Sets the tip area of tooltip to be the area covered by the item at path. See also set_tooltip_column() for a simpler alternative. See also Gtk.Tooltip.set_tip_area(). set_tooltip_cell(tooltip, path, cell) Sets the tip area of tooltip to the area which cell occupies in the item pointed to by path. See also Gtk.Tooltip.set_tip_area() See also set_tooltip_column() for a simpler alternative. get_tooltip_context(x, y, keyboard_tip) This function is supposed to be used in a “query-tooltip” signal handler for Gtk.IconView. The x, y and keyboard_tip values which are received in the signal handler, should be passed to this method without modiﬁcation. The return value indicates whether there is an icon view item at the given coordinates (True) or not (False) for mouse tooltips. For keyboard tooltips the item returned will be the cursor item. When True, then all of the items which have been returned will be set to point to that row and corresponding model. x and y will always be converted to be relative to the Gtk.IconView‘s bin_window if keyboard_tooltip is False. set_tooltip_column(column) If you only plan to have simple (text-only) tooltips on full items, you can use this function to have Gtk.IconView handle these automatically for you. column should be set to the column in the Gtk.IconView‘s model containing the tooltip texts, or -1 to disable this feature. When enabled, “has-tooltip” will be set to True and Gtk.IconView will connect a “query-tooltip” signal handler. Note that the signal handler sets the text with Gtk.Tooltip.set_markup(), so &, <, etc have to be escaped in the text. get_tooltip_column() Returns the column of Gtk.IconView‘s model which is being used for displaying tooltips on Gtk.IconView‘s rows, or -1 if this is disabled. get_item_row(path) Gets the row in which the item path is currently displayed. Row numbers start at 0. get_item_column(path) Gets the column in which the item path is currently displayed. Column numbers start at 0. enable_model_drag_source(start_button_mask, targets, n_targets, actions) Turns Gtk.IconView into a drag source for automatic DND. Calling this method sets “reorderable” to False. enable_model_drag_dest(targets, n_targets, actions) Turns Gtk.IconView into a drop destination for automatic DND. Calling this method sets “reorderable” to False. unset_model_drag_source() Undoes the effect of enable_model_drag_source(). Calling this method sets “reorderable” to False.

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unset_model_drag_dest() Undoes the effect of enable_model_drag_dest(). Calling this method sets “reorderable” to False. set_reorderable(reorderable) This method is a convenience method to allow you to reorder models that support the Gtk.TreeDragSource and the Gtk.TreeDragDest interfaces. Both Gtk.TreeStore and Gtk.ListStore support these. If reorderable is True, then the user can reorder the model by dragging and dropping rows. The developer can listen to these changes by connecting the model’s “row_inserted” and “row_deleted” signals. The reordering is implemented by setting up the icon view as drag source and destination. Therefore, drag and drop can not be used in a reorderable view for any other purpose. This function does not give you any degree of control over the order – any reordering is allowed. If more control is needed, you should probably handle drag and drop manually. get_reorderable() Retrieves whether the user can reorder the list via drag-and-drop. See set_reorderable(). set_drag_dest_item(path, pos) Sets the item that is highlighted for feedback. get_drag_dest_item() Gets information about the item that is highlighted for feedback. get_dest_item_at_pos(drag_x, drag_y) Determines the destination item for a given position. create_drag_icon(path) Creates a Cairo.Surface representation of the item at path. This image is used for a drag icon.

MULTILINE TEXT EDITOR
The Gtk.TextView widget can be used to display and edit large amounts of formatted text. Like the Gtk.TreeView, it has a model/view design. In this case the Gtk.TextBuffer is the model which represents the text being edited. This allows two or more Gtk.TextView widgets to share the same Gtk.TextBuffer, and allows those text buffers to be displayed slightly differently. Or you could maintain several text buffers and choose to display each one at different times in the same Gtk.TextView widget.

14.1 The View
The Gtk.TextView is the frontend with which the user can add, edit and delete textual data. They are commonly used to edit multiple lines of text. When creating a Gtk.TextView it contains its own default Gtk.TextBuffer, which you can access via the Gtk.TextView.get_buffer() method. By default, text can be added, edited and removed from the Gtk.TextView. You can disable this by calling Gtk.TextView.set_editable(). If the text is not editable, you usually want to hide the text cursor with Gtk.TextView.set_cursor_visible() as well. In some cases it may be useful to set the justiﬁcation of the text with Gtk.TextView.set_justification(). The text can be displayed at the left edge, (Gtk.Justification.LEFT), at the right edge (Gtk.Justification.RIGHT), centered (Gtk.Justification.CENTER), or distributed across the complete width (Gtk.Justification.FILL). Another default setting of the Gtk.TextView widget is long lines of text will continue horizontally until a break is entered. To wrap the text and prevent it going off the edges of the screen call Gtk.TextView.set_wrap_mode().

14.1.1 TextView Objects
class Gtk.TextView Creates a new Gtk.TextView associated with an empty default Gtk.TextBuffer. get_buffer() Returns the Gtk.TextBuffer being displayed by this text view. set_editable(editable) Sets the default editability of this Gtk.TextView. set_cursor_visible(visible) Toggles whether the insertion point is displayed. A buffer with no editable text probably shouldn’t have a visible cursor, so you may want to turn the cursor off. set_justification(justiﬁcation) Sets the default justiﬁcation of text.

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justiﬁcation can be one of the following values: •Gtk.Justification.LEFT: Text is placed at the left edge. •Gtk.Justification.RIGHT: Text is placed at the right edge. •Gtk.Justification.CENTER: Text is placed in the center. •Gtk.Justification.FILL: Text is distributed across the complete width. set_wrap_mode(wrap_mode) Sets the line wrapping for the view. wrap_mode can be one of the following values: •Gtk.WrapMode.NONE: Do not wrap lines; just make the text area wider. •Gtk.WrapMode.CHAR: Wrap text, breaking lines anywhere the cursor can appear (between characters, usually). •Gtk.WrapMode.WORD: Wrap text, breaking lines in between words. •Gtk.WrapMode.WORD_CHAR: Wrap text, breaking lines in between words, or if that is not enough, also between graphemes.

14.2 The Model
The Gtk.TextBuffer is the core of the Gtk.TextView widget, and is used to hold whatever text is being displayed in the Gtk.TextView. Setting and retrieving the contents is possible with Gtk.TextBuffer.set_text() and Gtk.TextBuffer.get_text(). However, most text manipulation is accomplished with iterators, represented by a Gtk.TextIter. An iterator represents a position between two characters in the text buffer. Iterators are not valid indeﬁnitely; whenever the buffer is modiﬁed in a way that affects the contents of the buffer, all outstanding iterators become invalid. Because of this, iterators can’t be used to preserve positions across buffer modiﬁcations. To preserve a position, use Gtk.TextMark. A text buffer contains two built-in marks; an “insert” mark (which is the position of the cursor) and the “selection_bound” mark. Both of them can be retrieved using Gtk.TextBuffer.get_insert() and Gtk.TextBuffer.get_selection_bound(), respectively. By default, the location of a Gtk.TextMark is not shown. This can be changed by calling Gtk.TextMark.set_visible(). Many methods exist to retrieve a Gtk.TextIter. For instance, Gtk.TextBuffer.get_start_iter() returns an iterator pointing to the ﬁrst position in the text buffer, whereas Gtk.TextBuffer.get_end_iter() returns an iterator pointing past the last valid character. Retrieving the bounds of the selected text can be achieved by calling Gtk.TextBuffer.get_selection_bounds(). To insert text at a speciﬁc position use Gtk.TextBuffer.insert(). Another useful method is Gtk.TextBuffer.insert_at_cursor() which inserts text wherever the cursor may be currently positioned. To remove portions of the text buffer use Gtk.TextBuffer.delete(). In addition, Gtk.TextIter can be used to locate textual matches in the buffer using Gtk.TextIter.forward_search() and Gtk.TextIter.backward_search(). The start and end iters are used as the starting point of the search and move forwards/backwards depending on requirements.

14.2.1 TextBuffer Objects
class Gtk.TextBuffer

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set_text(text[, length ]) Deletes current contents of this buffer, and inserts length characters of text instead. If length is -1 or omitted, text is inserted completely. get_text(start_iter, end_iter) Returns the text in the range start_iter (included) and end_iter (excluded). Excludes undisplayed text. get_insert() Returns the Gtk.TextMark that represents the cursor (insertion point). get_selection_bound() Returns the Gtk.TextMark that represents the selection bound. create_mark(mark_name, where[, left_gravity ]) Creates a Gtk.TextMark at the position of the Gtk.TextIter where. If mark_name is None, the mark is anonymous; otherwise, the mark can be retrieved by name using get_mark(). If a mark has left gravity, and text is inserted at the mark’s current location, the mark will be moved to the left of the newly-inserted text. If the mark has right gravity (left_gravity is False), the mark will end up on the right of newly-inserted text. The standard left-to-right cursor is a mark with right gravity (when you type, the cursor stays on the right side of the text you’re typing). If left_gravity is omitted, it defaults to False. get_mark(mark_name) Returns the Gtk.TextMark named name in this buffer, or None if no such mark exists in the buffer. get_start_iter() Returns a Gtk.TextIter pointing to ﬁrst position in this buffer. get_end_iter() Returns a Gtk.TextIter pointing past the last valid character in this buffer. get_selection_bounds() Returns a tuple of two Gtk.TextIter objects pointing to the ﬁrst character of the selection and to the ﬁrst character after the selection, respectively. If no text is selected an empty tuple is returned. insert(text_iter, text[, length ]) Inserts length characters of text at position text_iter. If length is -1 or omitted, text is inserted completely. insert_at_cursor(text[, length ]) Simply calls insert(), using the current cursor position as the insertion point. delete(start_iter, end_iter) Deletes text between start_iter and end_iter. create_tag(tag_name, **kwargs) Creates a tag and adds it to the tag table of this buffer. If tag_name is None, the tag is anonymous, otherwise a tag with the same name must not already exist in the tag table of the buffer. kwargs is an arbitrary number of key-value pairs that represent a list properties to set on the tag, as with tag.set_property(prop_name, value). apply_tag(tag, start_iter, end_iter) Applies tag to the given range. remove_tag(tag, start_iter, end_iter) Removes all occurrences of tag from the given range. remove_all_tags(start_iter, end_iter) Removes all tags in the given range.

14.2. The Model

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class Gtk.TextIter forward_search(needle, ﬂags, limit) Searches forward for needle. The search will not continue past the Gtk.TextIter limit. ﬂags can be set to one of the following, or any combination of it by concatenating them with the bitwise-OR operator |. •0: The match must be exact. •Gtk.TextSearchFlags.VISIBLE_ONLY: The match may have invisible text interspersed in needle. i.e. needle will be a possibly-noncontiguous subsequence of the matched range. •Gtk.TextSearchFlags.TEXT_ONLY: The match may have pixbufs or child widgets mixed inside the matched range. •Gtk.TextSearchFlags.CASE_INSENSITIVE: The text will be matched regardless of what case it is in. Returns a tupel containing a Gtk.TextIter pointing to the start and to the ﬁrst character after the match. If no match was found, None is returned. backward_search(needle, ﬂags, limit) Same as forward_search(), but moves backward. class Gtk.TextMark set_visible(visible) Sets the visibility of this mark; the insertion point is normally visible, i.e. you can see it as a vertical bar. Also, the text widget uses a visible mark to indicate where a drop will occur when dragging-and-dropping text. Most other marks are not visible. Marks are not visible by default.

14.3 Tags
Text in a buffer can be marked with tags. A tag is an attribute that can be applied to some range of text. For example, a tag might be called “bold” and make the text inside the tag bold. However, the tag concept is more general than that; tags don’t have to affect appearance. They can instead affect the behaviour of mouse and key presses, “lock” a range of text so the user can’t edit it, or countless other things. A tag is represented by a Gtk.TextTag object. One Gtk.TextTag can be applied to any number of text ranges in any number of buffers. Each tag is stored in a Gtk.TextTagTable. A tag table deﬁnes a set of tags that can be used together. Each buffer has one tag table associated with it; only tags from that tag table can be used with the buffer. A single tag table can be shared between multiple buffers, however. To specify that some text in the buffer should have speciﬁc formatting, you must deﬁne a tag to hold that formatting information, and then apply that tag to the region of text using Gtk.TextBuffer.create_tag() and Gtk.TextBuffer.apply_tag():
tag = textbuffer.create_tag("orange_bg", background="orange") textbuffer.apply_tag(tag, start_iter, end_iter)

The following are some of the common styles applied to text: • Background colour (“foreground” property) • Foreground colour (“background” property) • Underline (“underline” property)

MENUS
GTK+ comes with two different types of menus, Gtk.MenuBar and Gtk.Toolbar. Gtk.MenuBar is a standard menu bar which contains one or more Gtk.MenuItem instances or one of its subclasses. Gtk.Toolbar widgets are used for quick accessibility to commonly used functions of an application. Examples include creating a new document, printing a page or undoing an operation. It contains one or more instances of Gtk.ToolItem or one of its subclasses.

15.1 Actions
Although, there are speciﬁc APIs to create menus and toolbars, you should use Gtk.UIManager and create Gtk.Action instances. Actions are organised into groups. A Gtk.ActionGroup is essentially a map from names to Gtk.Action objects. All actions that would make sense to use in a particular context should be in a single group. Multiple action groups may be used for a particular user interface. In fact, it is expected that most non-trivial applications will make use of multiple groups. For example, in an application that can edit multiple documents, one group holding global actions (e.g. quit, about, new), and one group per document holding actions that act on that document (eg. save, cut/copy/paste, etc). Each window’s menus would be constructed from a combination of two action groups. Different classes representing different types of actions exist: • Gtk.Action: An action which can be triggered by a menu or toolbar item • Gtk.ToggleAction: An action which can be toggled between two states • Gtk.RadioAction: An action of which only one in a group can be active • Gtk.RecentAction: An action of which represents a list of recently used ﬁles Actions represent operations that the user can be perform, along with some information how it should be presented in the interface, including its name (not for display), its label (for display), an accelerator, whether a label indicates a stock item, a tooltip, as well as the callback that is called when the action gets activated. You can create actions by either calling one of the constructors directly and adding them to a Gtk.ActionGroup by calling Gtk.ActionGroup.add_action() or Gtk.ActionGroup.add_action_with_accel(), or by calling one of the convenience functions: • Gtk.ActionGroup.add_actions(), • Gtk.ActionGroup.add_toggle_actions() • Gtk.ActionGroup.add_radio_actions(). Note that you must specify actions for sub menus as well as menu items.

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15.1.1 Action Objects
class Gtk.Action(name, label, tooltip, stock_id) name must be a unique name of the action. If label is not None, it is displayed in menu items and on buttons. If tooltip is not None, it is used as tooltip for the action. If stock_id is not None, it is used to lookup the stock item to display in widgets representing the action. class Gtk.ToggleAction(name, label, tooltip, stock_id) The arguments are the same as for the Gtk.Action constructor. class Gtk.RadioAction(name, label, tooltip, stock_id, value) The ﬁrst four arguments are the same as for the Gtk.Action constructor. value indicates the value which get_current_value() should return if this action is selected. get_current_value() Obtains the “value” property of the currently active member of the group to which this action belongs. join_group(group_source) Joins this radio action object to the group of the group_source radio action object. group_source must be a radio action object whose group we are joining, or None to remove the radio action from its group. class Gtk.ActionGroup(name) Creates a new Gtk.ActionGroup instance. The name of the action group is used when associating keybindings with the actions. add_action(action) Adds an Gtk.Action object to the action group. Note that this method does not set add_action_with_accel() instead. up the accelerator path of the action, use

add_action_with_accel(action, accelerator) Adds an Gtk.Action object to the action group and sets up the accelerator. accelerator must be in the format understood by Gtk.accelerator_parse(), or "" for no accelerator, or None to use the stock accelerator. add_actions(entries[, user_data ]) This is a convenience function to create a number of Gtk.Action objects and add them to this action group. entries is a list of tuples which can vary in size from one to six items with the following information: •The name of the action (mandatory) •The stock item of the action (default: None) •The label for the action (default: None) •The accelerator for the action, in the format understood by the Gtk.accelerator_parse() function (default: None) •The tooltip of the action (default: None) •The callback function invoked when the action is activated (default: None) The “activate” signals of the actions are connected to the callbacks. If user_data is not None, it is passed to the callback function (if speciﬁed). 84 Chapter 15. Menus

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add_toggle_actions(entries[, user_data ]) This is a convenience function to create a number of Gtk.ToggleAction objects and add them to this action group. entries is a list of tuples which can vary in size from one to seven items with the following information: •The name of the action (mandatory) •The stock item of the action (default: None) •The label for the action (default: None) •The accelerator for the action, in the format understood by the Gtk.accelerator_parse() function (default: None) •The tooltip of the action (default: None) •The callback function invoked when the action is activated (default: None) •A Boolean indicating whether the toggle action is active (default: False) The “activate” signals of the actions are connected to the callbacks. If user_data is not None, it is passed to the callback function (if speciﬁed). add_radio_actions(entries[, value[, on_change[, user_data ]]]) This is a convenience routine to create a group of Gtk.RadioAction objects and add them to this action group. entries is a list of tuples which can vary in size from one to six items with the following information: •The name of the action (mandatory) •The stock item of the action (default: None) •The label for the action (default: None) •The accelerator for the action, in the format understood by the Gtk.accelerator_parse() function (default: None) •The tooltip of the action (default: None) •The value to set on the radio action (default: 0) value speciﬁes the radio action that should be set active. The “changed” signal of the ﬁrst radio action is connected to the on_change callback (if speciﬁed). If user_data is not None, it is passed to the callback function (if speciﬁed). Gtk.accelerator_parse(accelerator) Parses a string representing an accelerator. The format looks like “<Control>a” or “<Shift><Alt>F1” or “<Release>z” (the last one is for key release). The parser is fairly liberal and allows lower or upper case, and also abbreviations such as “<Ctl>” and “<Ctrl>”. For character keys the name is not the symbol, but the lowercase name, e.g. one would use “<Ctrl>minus” instead of “<Ctrl>-”. Returns a tuple (accelerator_key, accelerator_mods), where the latter represents the accelerator modiﬁer mask and the ﬁrst the accelerator keyval. Both values will be set to 0 (zero) if parsing failed.

15.2 UI Manager
Gtk.UIManager provides an easy way of creating menus and toolbars using an XML-like description.

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First of all, you should add the Gtk.ActionGroup to the UI Manager with Gtk.UIManager.insert_action_group(). At this point is also a good idea to tell the parent window to respond to the speciﬁed keyboard shortcuts, by using Gtk.UIManager.get_accel_group() and Gtk.Window.add_accel_group(). Then, you can deﬁne the actual visible layout of the menus and toolbars, and add the UI layout. This “ui string” uses an XML format, in which you should mention the names of the actions that you have already created. Remember that these names are just the identiﬁers that we used when creating the actions. They are not the text that the user will see in the menus and toolbars. We provided those human-readable names when we created the actions. Finally, you retrieve the root widget with Gtk.UIManager.get_widget() and add the widget to a container such as Gtk.Box.

15.2.1 UIManager Objects
class Gtk.UIManager insert_action_group(action_group[, pos ]) Inserts an action group into the list of action groups associated with this manager. Actions in earlier groups hide actions with the same name in later groups. pos is the position at which the group will be inserted. If omitted, it will be appended. get_accel_group() Returns the group of global keyboard accelerators associated with this manager. get_widget(path) Looks up a widget by following a path. The path consists of the names speciﬁed in the XML description of the UI. separated by ‘/’. Elements which don’t have a name or action attribute in the XML (e.g. <popup>) can be addressed by their XML element name (e.g. “popup”). The root element (“/ui”) can be omitted in the path. Returns the widget found by following the path, or None if no widget was found. add_ui_from_string(text) Parses text containing a UI deﬁnition and merges it with the current contents of manager. An enclosing <ui> element is added if it is missing. Returns the merge id for the merged UI. Throws an exception if an error occurred.

DIALOGS
Dialog windows are very similar to standard windows, and are used to provide or retrieve information from the user. They are often used to provide a preferences window, for example. The major difference a dialog has is some prepacked widgets which layout the dialog automatically. From there, we can simply add labels, buttons, check buttons, etc. Another big difference is the handling of responses to control how the application should behave after the dialog has been interacted with. There are several derived Dialog classes which you might ﬁnd useful. Gtk.MessageDialog is used for most simple notiﬁcations. But at other times you might need to derive your own dialog class to provide more complex functionality.

16.1 Custom Dialogs
To pack widgets into a custom dialog, you should pack them into the Gtk.Box, available via Gtk.Dialog.get_content_area(). To just add a Gtk.Button to the bottom of the dialog, you could use the Gtk.Dialog.add_button() method. A ‘modal’ dialog (that is, one which freezes the rest of the application from user input), can be created by calling Gtk.Dialog.set_modal on the dialog or set the flags argument of the Gtk.Dialog constructor to include the Gtk.DialogFlags.MODAL ﬂag. Clicking a button will emit a signal called “response”. If you want to block waiting for a dialog to return before returning control ﬂow to your code, you can call Gtk.Dialog.run(). This method returns an int which may be a value from the Gtk.ResponseType or it could be the custom response value that you speciﬁed in the Gtk.Dialog constructor or Gtk.Dialog.add_button(). Finally, there are two ways to remove a dialog. The Gtk.Widget.hide() method removes the dialog from view, however keeps it stored in memory. This is useful to prevent having to construct the dialog again if it needs to be accessed at a later time. Alternatively, the Gtk.Widget.destroy() method can be used to delete the dialog from memory once it is no longer needed. It should be noted that if the dialog needs to be accessed after it has been destroyed, it will need to be constructed again otherwise the dialog window will be empty.

16.1.1 Dialog Objects
class Gtk.Dialog([title[, parent[, ﬂags[, buttons]]]) Creates a new Gtk.Dialog with title title and transient parent parent. The ﬂags argument can be used to make the dialog model (Gtk.DialogFlags.MODAL) and/or to have it destroyed along with its transient parent (Gtk.DialogFlags.DESTROY_WITH_PARENT). buttons is a tuple of buttons which can be set to provide a range of different buttons and responses. See the add_button() method for details.

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All arguments are optional and can be referred to as key-word arguments as well. get_content_area() Return the content area of of this dialog. add_button(button_text, response_id) Adds a button with the given text (or a stock button, if button_text is a stock item) and sets things up so that clicking the button will emit the “response” signal with the given response_id. The button is appended to the end of the dialog’s action area. response_id can be any positive integer or one of the predeﬁned Gtk.ResponseType values: •Gtk.ResponseType.NONE •Gtk.ResponseType.REJECT •Gtk.ResponseType.ACCEPT •Gtk.ResponseType.DELETE_EVENT •Gtk.ResponseType.OK •Gtk.ResponseType.CANCEL •Gtk.ResponseType.CLOSE •Gtk.ResponseType.YES •Gtk.ResponseType.NO •Gtk.ResponseType.APPLY •Gtk.ResponseType.HELP The button widget is returned, but usually you don’t need it. add_buttons(button_text, response_id[, ... ]) Adds several buttons to this dialog using the button data passed as arguments to the method. This method is the same as calling add_button() repeatedly. The button data pairs - button text (or stock item) and a response ID integer are passed individually. For example:
dialog.add_buttons(Gtk.STOCK_OPEN, 42, "Close", Gtk.ResponseType.CLOSE)

set_modal(is_modal) Sets a dialog modal or non-modal. Modal dialogs prevent interaction with other windows in the same application. run() Blocks in a recursive main loop until the dialog either emits the “response” signal, or is destroyed. If the dialog is destroyed during the call to run(), run() returns Gtk.ResponseType.NONE. Otherwise, it returns the response ID from the “response” signal emission.

16.2 MessageDialog
Gtk.MessageDialog is a convenience class, used to create simple, standard message dialogs, with a message, an icon, and buttons for user response You can specify the type of message and the text in the Gtk.MessageDialog constructor, as well as specifying standard buttons. In some dialogs which require some further explanation of what has happened, a secondary text can be added. In this case, the primary message entered when creating the message dialog is made bigger and set to bold text. The secondary message can be set by calling Gtk.MessageDialog.format_secondary_text().

16.2.1 MessageDialog Objects
class Gtk.MessageDialog([parent[, ﬂags[, message_type[, buttons, [message_format]]]]) Creates a new Gtk.MessageDialog with transient parent parent. The ﬂags argument can be used to make the dialog model (Gtk.DialogFlags.MODAL) and/or to have it destroyed along with its transient parent (Gtk.DialogFlags.DESTROY_WITH_PARENT). message_type can be set to one of the following values: •Gtk.MessageType.INFO: Informational message •Gtk.MessageType.WARNING: Non-fatal warning message •Gtk.MessageType.QUESTION: Question requiring a choice •Gtk.MessageType.ERROR: Fatal error message •Gtk.MessageType.OTHER: None of the above, doesn’t get an icon It is also possible to set a variety of buttons on the message dialog, to retrieve different responses from the user. One of the following values can be used: •Gtk.ButtonsType.NONE: no buttons at all •Gtk.ButtonsType.OK: an OK button •Gtk.ButtonsType.CLOSE: a Close button •Gtk.ButtonsType.CANCEL: a Cancel button •Gtk.ButtonsType.YES_NO: Yes and No buttons •Gtk.ButtonsType.OK_CANCEL: OK and Cancel buttons Finally, message_format is some text that the user may want to see. All arguments are optional and can be referred to as key-word arguments as well. format_secondary_text(message_format) Sets the secondary text of the message dialog to be message_format. Note that setting a secondary text makes the primary text (message_format argument of Gtk.MessageDialog constructor) become bold, unless you have provided explicit markup.

16.3 FileChooserDialog
The Gtk.FileChooserDialog is suitable for use with “File/Open” or “File/Save” menu items. You can use all of the Gtk.FileChooser methods on the ﬁle chooser dialog as well as those for Gtk.Dialog. When creating a Gtk.FileChooserDialog you have to deﬁne the dialog’s purpose: • To select a ﬁle for opening, as for a File/Open command, use Gtk.FileChooserAction.OPEN • To save a ﬁle for the ﬁrst time, as for a File/Save command, use Gtk.FileChooserAction.SAVE, and suggest a name such as “Untitled” with Gtk.FileChooser.set_current_name(). • To save a ﬁle under a different use Gtk.FileChooserAction.SAVE, Gtk.FileChooser.set_filename(). name, and as set for a File/Save As command, the existing ﬁlename with

• To choose a folder instead of a ﬁle, use Gtk.FileChooserAction.SELECT_FOLDER. Gtk.FileChooserDialog inherits from Gtk.Dialog, so buttons have response IDs such as Gtk.ResponseType.ACCEPT and Gtk.ResponseType.CANCEL which can be speciﬁed in the

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Gtk.FileChooserDialog constructor. In contrast to Gtk.Dialog, you can not use custom response codes with Gtk.FileChooserDialog. It expects that at least one button will have of the following response IDs: • Gtk.ResponseType.ACCEPT • Gtk.ResponseType.OK • Gtk.ResponseType.YES • Gtk.ResponseType.APPLY When the user is ﬁnished selecting ﬁles, your program can get the selected names either as ﬁlenames (Gtk.FileChooser.get_filename()) or as URIs (Gtk.FileChooser.get_uri()). By default, Gtk.FileChooser only allows a single ﬁle to be selected at a time. To enable multiple ﬁles to be selected, use Gtk.FileChooser.set_select_multiple(). Retrieving a list of selected ﬁles is possible with either Gtk.FileChooser.get_filenames() or Gtk.FileChooser.get_uris(). Gtk.FileChooser also supports a variety of options which make the ﬁles and folders more conﬁgurable and accessible. • Gtk.FileChooser.set_local_only(): Only local ﬁles can be selected. • Gtk.FileChooser.show_hidden(): Hidden ﬁles and folders are displayed. • Gtk.FileChooser.set_do_overwrite_confirmation(): If the ﬁle chooser was conﬁgured in Gtk.FileChooserAction.SAVE mode, it will present a conﬁrmation dialog if the user types a ﬁle name that already exists. Furthermore, you can specify which kind of ﬁles are displayed by creating Gtk.FileFilter objects and calling Gtk.FileChooser.add_filter(). The user can then select one of the added ﬁlters from a combo box at the bottom of the ﬁle chooser.

16.3.1 FileChooser Objects
class Gtk.FileChooserDialog([title[, parent[, action[, buttons]]]) Creates a new Gtk.FileChooserDialog with title title and transient parent *parent. action can be one of the following: •Gtk.FileChooserAction.OPEN: The ﬁle chooser will only let the user pick an existing ﬁle. •Gtk.FileChooserAction.SAVE: The ﬁle chooser will let the user pick an existing ﬁle, or type in a new ﬁlename. •Gtk.FileChooserAction.SELECT_FOLDER: The ﬁle chooser will let the user pick an existing folder. •Gtk.FileChooserAction.CREATE_FOLDER: The ﬁle chooser will let the user name an existing or new folder. The buttons argument has the same format as for the Gtk.Dialog constructor. class Gtk.FileChooser set_current_name(name) Sets the current name in the ﬁle selector, as if entered by the user. set_filename(ﬁlename) Sets ﬁlename as the current ﬁlename for the ﬁle chooser, by changing to the ﬁle’s parent folder and actually selecting the ﬁle in list; all other ﬁles will be unselected. If the chooser is in

16.3. FileChooserDialog

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Gtk.FileChooserAction.SAVE mode, the ﬁle’s base name will also appear in the dialog’s ﬁle name entry. Note that the ﬁle must exist, or nothing will be done except for the directory change. set_select_multiple(select_multiple) Sets whether multiple ﬁles can be selected. This is only relevant if the mode is Gtk.FileChooserAction.OPEN or Gtk.FileChooserAction.SELECT_FOLDER. set_local_only(local_only) Sets whether only local ﬁles can be selected. set_show_hidden(show_hidden) Sets whether to display hidden ﬁles and folders. set_do_overwrite_confirmation(do_overwrite_conﬁrmation) Sets whether to conﬁrm overwriting in save mode. get_filename() Returns the ﬁlename for the currently selected ﬁle in the ﬁle selector. If multiple ﬁles are selected, use get_filenames() instead. get_filenames() Returns a list of all the selected ﬁles and subfolders in the current folder. The returned names are full absolute paths. If ﬁles in the current folder cannot be represented as local ﬁlenames they will be ignored. Use get_uris() instead. get_uri() Returns the URI for the currently selected ﬁle in the ﬁle selector. If multiple ﬁles are selected, use get_uris() instead. get_uris() Returns a list of all the selected ﬁles and subfolders in the current folder. The returned names are full absolute URIs. add_filter(ﬁlter) Adds the Gtk.FileFilter instance ﬁlter to the list of ﬁlters that the user can choose from. When a ﬁlter is selected, only ﬁles that are passed by that ﬁlter are displayed. class Gtk.FileFilter set_name(name) Sets the human-readable name of the ﬁlter; this is the string that will be displayed in the ﬁle selector user interface if there is a selectable list of ﬁlters. add_mime_type(mime_type) Adds a rule allowing a given mime type to ﬁlter. add_pattern(pattern) Adds a rule allowing a shell style glob to a ﬁlter.

CLIPBOARD
Gtk.Clipboard provides a storage area for a variety of data, including text and images. Using a clipboard allows this data to be shared between applications through actions such as copying, cutting, and pasting. These actions are usually done in three ways: using keyboard shortcuts, using a Gtk.MenuItem, and connecting the functions to Gtk.Button widgets. There are multiple clipboard selections for different purposes. In most circumstances, the selection named CLIPBOARD is used for everyday copying and pasting. PRIMARY is another common selection which stores text selected by the user with the cursor.

17.1 Clipboard Objects
class Gtk.Clipboard get(selection) Obtains the Gtk.Clipboard for the given selection. selection is a Gdk.Atom describing which clipboard to use. Predeﬁned values include: •Gdk.SELECTION_CLIPBOARD •Gdk.SELECTION_PRIMARY set_text(text, length) Sets the contents of the clipboard to the given text. text is the string to put in the clipboard. length is the number of characters to store. It may be omitted to store the entire string. set_image(image) Sets the contents of the clipboard to the given image. image must be a Gdk.Pixbuf. To retrieve one from a Gdk.Image, use image.get_pixbuf(). wait_for_text() Returns the clipboard’s content as a string, or returns None if the clipboard is empty or not currently holding text. wait_for_image() Returns the clipboard’s content as a Gtk.Pixbuf, or returns None if the clipboard is empty or not currently holding an image.

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store() Stores the clipboard’s data outside the application. Otherwise, data copied to the clipboard may be lost when the application exits. clear() Clears the contents of the clipboard. Use with caution; this may clear data from another application.

DRAG AND DROP
Note: Versions of PyGObject < 3.0.3 contain a bug which does not allow drag and drop to function correctly. Therefore a version of PyGObject >= 3.0.3 is required for the following examples to work. Setting up drag and drop between widgets consists of selecting a drag source (the widget which the user starts the drag from) with the Gtk.Widget.drag_source_set() method, selecting a drag destination (the widget which the user drops onto) with the Gtk.Widget.drag_dest_set() method and then handling the relevant signals on both widgets. Instead of using Gtk.Widget.drag_source_set() and Gtk.Widget.drag_dest_set() some specialised widgets require the use of speciﬁc functions (such as Gtk.TreeView and Gtk.IconView). A basic drag and drop only requires the source to connect to the “drag-data-get” signal and the destination to connect to the “drag-data-received” signal. More complex things such as speciﬁc drop areas and custom drag icons will require you to connect to additional signals and interact with the Gdk.DragContext object it supplies. In order to transfer data between the source and destination, you must interact with the Gtk.SelectionData variable supplied in the “drag-data-get” and “drag-data-received” signals using the Gtk.SelectionData get and set methods.

18.1 Target Entries
To allow the drag source and destination to know what data they are receiving and sending, a common list of Gtk.TargetEntry’s are required. A Gtk.TargetEntry describes a piece of data that will be sent by the drag source and received by the drag destination. There are two ways of adding Gtk.TargetEntry’s to a source and destination. If the drag and drop is simple and each target entry is of a different type, you can use the group of methods mentioned here. If you require more than one type of data or wish to do more complex things with the data, you will need to create the Gtk.TargetEntry’s using the Gtk.TargetEntry.new() method.

Sets the widget to be a drag source. start_button_mask are a combination of Gdk.ModifierType masks which sets which buttons must be pressed for a drag to occur. targets is a list of Gtk.TargetEntry’s which describe the data to be passed between source and destination. actions are a combination Gdk.DragAction masks to show possible drag actions. drag_dest_set(ﬂags, targets, actions) Sets the widget to be a drag destination. ﬂags are a combination of Gtk.DestDefaults masks which conﬁgures the processes which occur on a drag site. targets is a list of Gtk.TargetEntry’s which describe the data to be passed between source and destination. actions are a combination Gdk.DragAction masks to show possible drag actions. drag_source_add_text_targets() drag_dest_add_text_targets() Add a Gtk.TargetEntry to the drag source/destination which contains a piece of text. drag_source_add_image_targets() drag_dest_add_image_targets() Add a Gtk.TargetEntry to the drag source/destination which contains a GdkPixbuf.Pixbuf. drag_source_add_uri_targets() drag_dest_add_uri_targets() Add a Gtk.TargetEntry to the drag source/destination which contains a list of URIs. class Gtk.TargetEntry static new(target, ﬂags, info) Creates a new target entry. target is a string describing the type of data the target entry describes. ﬂags controls under which conditions will the data be transferred in a drag and drop and is a combination of the Gtk.TargetFlags values: •Gtk.TargetFlags.SAME_APP - Only transferred in the same application •Gtk.TargetFlags.SAME_WIDGET - Only transferred within the same widget •Gtk.TargetFlags.OTHER_APP - Only transferred in a different application •Gtk.TargetFlags.OTHER_WIDGET - Only transferred within a different widget info is an ID which the application can use to determine between different pieces of data contained in a drag and drop operation. class Gtk.SelectionData get_text() Returns the contents of the text contained in selection data set_text(text) Sets the contents of the text contained in selection data to text get_pixbuf() Returns the pixbuf contained in selection data

18.3 Drag Source Signals
Name drag-begin drag-dataget drag-datadelete drag-dataend When it is emitted User starts a drag When drag data is requested by the destination When a drag with the action Gdk.DragAction.MOVE is completed When the drag is complete Common Purpose Set-up drag icon Transfer drag data from source to destination Delete data from the source to complete the ‘move’ Undo anything done in drag-begin

18.4 Drag Destination Signals
Name drag-motion drag-drop drag-data-received When it is emitted Drag icon moves over a drop area Icon is dropped onto a drag area When drag data is received by the destination Common Purpose Allow only certain areas to be dropped onto Allow only certain areas to be dropped onto Transfer drag data from source to destination

GLADE AND GTK.BUILDER
The Gtk.Builder class offers you the opportunity to design user interfaces without writing a single line of code. This is possible through describing the interface by a XML ﬁle and then loading the XML description at runtime and create the objects automatically, which the Builder class does for you. For the purpose of not needing to write the XML manually the Glade application lets you create the user interface in a WYSIWYG (what you see is what you get) manner This method has several advantages: • Less code needs to be written. • UI changes can be seen more quickly, so UIs are able to improve. • Designers without programming skills can create and edit UIs. • The description of the user interface is independent from the programming language being used. There is still code required for handling interface changes triggered by the user, but Gtk.Builder allows you to focus on implementing that functionality.

19.1 Creating and loading the .glade ﬁle
First of all you have to download and install Glade. There are several tutorials about Glade, so this is not explained here in detail. Let’s start by creating a window with a button in it and saving it to a ﬁle named example.glade. The resulting XML ﬁle should look like this.
<?xml version="1.0" encoding="UTF-8"?> <interface> <!-- interface-requires gtk+ 3.0 --> <object class="GtkWindow" id="window1"> <property name="can_focus">False</property> <child> <object class="GtkButton" id="button1"> <property name="label" translatable="yes">button</property> <property name="use_action_appearance">False</property> <property name="visible">True</property> <property name="can_focus">True</property> <property name="receives_default">True</property> <property name="use_action_appearance">False</property> </object> </child> </object> </interface>

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To load this ﬁle in Python we need a Gtk.Builder object.
builder = Gtk.Builder() builder.add_from_file("example.glade")

The second line loads all objects deﬁned in example.glade into the Builder object. It is also possible to load only some of the objects. The following line would add only the objects (and their child objects) given in the tuple.
# we don’t really have two buttons here, this is just an example builder.add_objects_from_file("example.glade", ("button1", "button2"))

These two methods exist also for loading from a string rather than a ﬁle. Their corresponding names are Gtk.Builder.add_from_string() and Gtk.Builder.add_objects_from_string() and they simply take a XML string instead of a ﬁle name.

19.2 Accessing widgets
Now that the window and the button are loaded we also want to show them. Therefore the Gtk.Window.show_all() method has to be called on the window. But how do we access the associated object?
window = builder.get_object("window1") window.show_all()

Every widget can be retrieved from the builder by the Gtk.Builder.get_object() method and the widget’s id. It is really that simple. It is also possible to get a list of all objects with
builder.get_objects()

19.3 Connecting Signals
Glade also makes it possible to deﬁne signals which you can connect to handlers in your code without extracting every object from the builder and connecting to the signals manually. The ﬁrst thing to do is to declare the signal names in Glade. For this example we will act when the window should be closed and when the button was pressed, so we give the name “onDeleteWindow” to the “delete-event” signal of the window and “onButtonPressed” to the “pressed” signal of the button. Now the XML ﬁle should look like this.
<?xml version="1.0" encoding="UTF-8"?> <interface> <!-- interface-requires gtk+ 3.0 --> <object class="GtkWindow" id="window1"> <property name="can_focus">False</property> <signal name="delete-event" handler="onDeleteWindow" swapped="no"/> <child> <object class="GtkButton" id="button1"> <property name="label" translatable="yes">button</property> <property name="use_action_appearance">False</property> <property name="visible">True</property> <property name="can_focus">True</property> <property name="receives_default">True</property> <property name="use_action_appearance">False</property>

Now we have to deﬁne the handler functions in our code. The onDeleteWindow should simply result in a call to Gtk.main_quit(). When the button is pressed we would like to print the string “Hello World!”, so we deﬁne the handler as follows
def hello(button): print "Hello World!"

Next, we have to connect the signals and the handler functions. The easiest way to do this is to deﬁne a dict with a mapping from the names to the handlers and then pass it to the Gtk.Builder.connect_signals() method.
handlers = { "onDeleteWindow": Gtk.main_quit, "onButtonPressed": hello } builder.connect_signals(handlers)

An alternative approach is to create a class which has methods that are called like the signals. In our example the last code snippet could be rewritten as:
1 2 3 4 5 6 7 8 9 10

19.4 Builder Objects
class Gtk.Builder add_from_file(ﬁlename) Loads and parses the given ﬁle and merges it with the current contents of builder. add_from_string(string) Parses the given string and merges it with the current contents of builder.. add_objects_from_file(ﬁlename, object_ids) Same as Gtk.Builder.add_from_file(), but loads only the objects with the ids given in the object_ids list. add_objects_from_string(ﬁlename, object_ids) Same as Gtk.Builder.add_from_string(), but loads only the objects with the ids given in the object_ids list. get_object(object_id) Retrieves the widget with the id object_id from the loaded objects in the builder.

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get_objects() Returns all loaded objects. connect_signals(handler_object) Connects the signals to the methods given in the handler_object. The handler_object can be any object which contains keys or attributes that are called like the signal handler names given in the interface description, e.g. a class or a dict.

OBJECTS
GObject is the fundamental type providing the common attributes and methods for all object types in GTK+, Pango and other libraries based on GObject. The GObject.GObject class provides methods for object construction and destruction, property access methods, and signal support. This section will introduce some important aspects about the GObject implementation in python.

20.1 Inherit from GObject.GObject
A native GObject is accessible via GObject.GObject. It is rarely intanciated directly, we generally use inherited class. A Gtk.Widget is an inherited class of a GObject.GObject. It may be interesting to make an inherited class to create a new widget, like a settings dialog. To inherit from GObject.GObject, you must call GObject.GObject.__init__() in your constructor (if the class inherits from Gtk.Button, it must call Gtk.Button.__init__() for instance), like in the example below:
from gi.repository import GObject class MyObject(GObject.GObject): def __init__(self): GObject.GObject.__init__(self)

20.2 Signals
Signals connect arbitrary application-speciﬁc events with any number of listeners. For example, in GTK+, every user event (keystroke or mouse move) is received from the X server and generates a GTK+ event under the form of a signal emission on a given object instance. Each signal is registered in the type system together with the type on which it can be emitted: users of the type are said to connect to the signal on a given type instance when they register a function to be invoked upon the signal emission. Users can also emit the signal by themselves or stop the emission of the signal from within one of the functions connected to the signal.

20.2.1 Receive signals
See Main loop and Signals

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20.2.2 Create new signals
New signals can be created by adding them to GObject.GObject.__gsignals__, a dictionary: When a new signal is created, a method handler can also be deﬁned, it will be called each time the signal is emitted. It is called do_signal_name.
class MyObject(GObject.GObject): __gsignals__ = { ’my_signal’: (GObject.SIGNAL_RUN_FIRST, None, (int,)) } def do_my_signal(self, arg): print "class method for ‘my_signal’ called with argument", arg

GObject.SIGNAL_RUN_FIRST indicates ths signal will invoke the object method handler (do_my_signal() here) in the ﬁrst emission stage. Alternatives are GObject.SIGNAL_RUN_LAST (the method handler will be invoked in the third emission stage) and GObject.SIGNAL_RUN_CLEANUP (invoke the method handler in the last emission stage). The second part, None, indicates the return type of the signal, usually None. (int,) indicates the signal arguments, here, the signal will only take one argument, whose type is int. This argument type list must end with a comma. Signals can be emitted using GObject.GObject.emit():
my_obj.emit("my_signal", 42) # emit the signal "my_signal", with the # argument 42

20.3 Properties
One of GObject’s nice features is its generic get/set mechanism for object properties. Each class inherited from GObject.GObject can deﬁne new properties. Each property as a type which never changes (e.g. str, ﬂoat, int...). For instance, they are used for Gtk.Button where there is a “label” property which contains the text of the button.

Some properties also have functions dedicated to them, called getter and setter. For the property “label” of a button, there are two functions to get and set them, Gtk.Button.get_label() and Gtk.Button.set_label().

20.3.2 Create new properties
A property is deﬁned with a name and a type. Even is python itself is dynamically typed, you can’t change the type of a property once it is deﬁned. A property can be created using GObject.property().
from gi.repository import GObject class MyObject(GObject.GObject): foo = GObject.property(type=str, default=’bar’)

Properties can also be readonly, if you want some properties to be readable but not writable. To do so, you can add some ﬂags to the property deﬁnition, to control read/write access. Flags are GObject.PARAM_READABLE (only read access for external code), GObject.PARAM_WRITABLE (only write access), GObject.PARAM_READWRITE (public):
foo = GObject.property(type=str, flags = GObject.PARAM_READABLE) # won’t be writable bar = GObject.property(type=str, flags = GObject.PARAM_WRITABLE) # won’t be readable

You can also deﬁne new read-only properties with a new method decorated with GObject.property():
from gi.repository import GObject class MyObject(GObject.GObject): def __init__(self): GObject.GObject.__init__(self) @GObject.property def readonly(self): return ’This is readonly.’

You can get this property using:
my_object = MyObject() print my_object.readonly print my_object.get_property("readonly")

freeze_notify() This method freezes all the “notify::” signals (which are emitted when any property is changed) until the thaw_notify() method is called. thaw_notify() Thaw all the “notify::” signals which were thawed by freeze_notify(). __gsignals__ A dictionary where inherited class can deﬁne new signals. Each element in the dictionary is a new signal. The key is the signal name. The value is a tuple, with the form:
(GObject.SIGNAL_RUN_FIRST, None, (int,))

GObject.SIGNAL_RUN_FIRST can be replaced with GObject.SIGNAL_RUN_LAST or GObject.SIGNAL_RUN_CLEANUP. None is the return type of the signal. (int,) is the list of the parameters of the signal, it must end with a comma.

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__gproperties__ The __gproperties__ dictionary is a class property where you deﬁne the properties of your object. This is not the recommend way to deﬁne new properties, the method written above is much less verbose. The beneﬁts of this method is that a property can be deﬁned with more settings, like the minimum or the maximum for numbers. The key is the name of the property The value is a tuple which describe the property. The number of elements of this tuple depends on its ﬁrst element but the tuple will always contain at least the following items: The ﬁrst element is the property’s type (e.g. int, float...). The second element is the property’s nick name, which is a string with a short description of the property. This is generally used by programs with strong introspection capabilities, like the graphical user interface builder Glade. The third one is the property’s description or blurb, which is another string with a longer description of the property. Also used by Glade and similar programs. The last one (which is not necessarily the forth one as we will see later) is the property’s ﬂags: GObject.PARAM_READABLE, GObject.PARAM_WRITABLE, GObject.PARAM_READWRITE. The absolute length of the tuple depends on the property type (the ﬁrst element of the tuple). Thus we have the following situations: If the type is bool or str, the forth element is the default value of the property. If the type is int or float, the forth element is the minimum accepted value, the ﬁfth element is the maximum accepted value and the sixth element is the default value. If the type is not one of these, there is no extra element. GObject.SIGNAL_RUN_FIRST Invoke the object method handler in the ﬁrst emission stage. GObject.SIGNAL_RUN_LAST Invoke the object method handler in the third emission stage. GObject.SIGNAL_RUN_CLEANUP Invoke the object method handler in the last emission stage. GObject.PARAM_READABLE The property is readable. GObject.PARAM_WRITABLE The property is writable. GObject.PARAM_READWRITE The property is readable and writable.

20.4. API

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STOCK ITEMS
Stock items represent commonly-used menu or toolbar items such as “Open” or “Exit”. Each stock item is identiﬁed by a stock ID; stock IDs are just strings, but constants such as Gtk.STOCK_OPEN are provided to avoid typing mistakes in the strings. Gtk.STOCK_ABOUT